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Full text of "The commercial granites of North Carolina"

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NORTH CAROLINA 
DEPARTMENT OF CONSERVATION AND DEVELOPMENT 

BEN E. DOUGLAS, DIRECTOR 



&£ 



DIVISION OF MINERAL RESOURCES 

JASPER L. STUCKEY, STATE GEOLOGIST 



Bulletin Number 67 



THE COMMERCIAL GRANITES 
OF NORTH CAROLINA 



BY 
RICHARD J. COUNCILL 



UN 1 1 



&» 



RALEIGH 
1954 



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•^^CAHounas 



SSU^UBftwy 



North Carolina 
Department of Conservation and Development 

Ben E. Douglas, Director 




Division of Mineral Resources 
Jasper L. Stuckey,- State Geologist 



Bulletin Number 67 



THE COMMERCIAL GRANITES 
OF NORTH CAROLINA 



By 

Richard J. Councill 



Raleigh 
1954 



MEMBERS OF THE BOARD OF CONSERVATION 
AND DEVELOPMENT 

Governor William B. Umstead, Chairman . Raleigh 

Miles J. Smith, First Vice Chairman Salisbury 

Walter J. Damtoft, Second Vice Chairman Canton 

Charles S. Allen Durham 

W. B. Austin Jefferson 

Carl Buchan, Jr North Wilkesboro 

Scroop W. Enloe, Jr Spruce Pine 

Robert M. Hanes Winston-Salem 

Leo H. Harvey Kinston 

Charles H. Jenkins : Ahoskie 

Amos R. Kearns High Point 

Cecil Morris Atlantic 

Hugh M. Morton Wilmington 

Henry Rankin, Jr Fayetteville 

Eric W. Rodgers Scotland Neck 

T. Max Watson Spindale 



11 



LETTER OF TRANSMITTAL 



Raleigh, North Carolina 
February 15, 1954 

To His Excellency, Governor William B. Umstead 
Governor of North Carolina 

Sir: 

I have the honor to submit herewith manuscript for publi- 
cation as Bulletin No. 67, "The Commercial Granites of North 
Carolina," by Richard J. Councill. 

Bulletin No. 2, "The Building and Ornamental Stones of 
North Carolina," which was published in 1906, has been out of 
print for several years. The importance of granite as a building 
material has increased rapidly in recent years. North Carolina 
is well supplied with granite, and it is believed that this report 
will be of considerable value to those interested in the granite 
resources of the State. 

Respectfully submitted, 

Ben E. Douglas, 

Director 



lxJ 



TABLE OF CONTENTS 

Page 

Introduction 1 

Methods of investigation and acknowledgments 1 

Granite defined 2 

Origin of granite 3 

Dikes penetrating the granites 3 

Acid dikes and veins 4 

Basic dikes 4 

Schistose dikes 4 

Diabase dikes 4 

Physical and structural properties of granite 5 

Dimension stone 5 

General ..' 5 

Dikes and veins : 5 

Segregations and inclusions 5 

Texture 5 

Rift and grain 6 

Sheeting 6 

Color , 6 

Joints 6 

Crushed stone 6 

General 6 

Toughness and hardness 6 

Soundness _■ 8 

Geographic distribution of granite and related rocks 8 

Blue Ridge 8 

Piedmont Plateau 8 

Coastal Plain 8 

Granites of the Coastal Plain 10 

Wilson County 10 

Contentnea Creek area 10 

Sims area 10 

Elm City area . 11 

Edgecombe and Nash Counties 12 

Pitt County 12 

Fountain area 12 

Anson and Richmond Counties 13 

The Wadesboro-Rockingham area 13 

Basic dikes 14 

Granites of the Piedmont Plateau 14 

Northeast Piedmont 14 

Central Piedmont 14 

Western Piedmont 14 

Granites of the Northeast Piedmont 16 

Wake County 17 

Raleigh granite area , 17 

The city quarries 17 

The Sutton quarry . 17 

Other quarries 17 

The Crabtree quarry : 17 

Rolesville granite area 18 

Dimension stone quarry 18 

Lassiter quarry 18 

Wendell granite area '. 18 

Knightdale granite area 20 

Abandoned quarry 20 

Other granite and granite-gneiss areas in Wake County 20 

Zebulon 20 

Wake Forest , 20 

Falls 20 

iv 



TABLE OF CONTENTS — CONTINUED 

Page 

Vance County 21 

Greystone quarry 21 

Middleburg quarry : 21 

Other granite areas in Vance County 22 

Franklin County 22 

The Louisburg area :. 22 

Dimension stone quarry 22 

Basic dikes 23 

Warren County 23 

Warrenton area 23 

Warren Plains area 23 

Warren County State quarry 23 

Old quarry 24 

Granville County 24 

State quarry 24 

Northampton County .____ 24 

The Henrico area 24 

Orange County 25 

The Bacon quarry 25 

Other Counties 26 

Granites of the Central Piedmont 26 

Rowan County 28 

The Harris granite quarries 28 

The Balfour quarry 29 

The Carolina quarry 30 

The Dunns Mountain quarries 30 

The American quarry 30 

The Shuping quarry 30 

The old Rowan Granite Company's quarries 31 

Quarries of the Salisbury Granite Industries, Inc 31 

The J. A. Logan Granite Company's quarry 33 

Other dimension stone quarries 33 

The Barnhardt quarry 33 

The Bear Poplar gabbro quarry 34 

The Woodleaf quarry 34 

Other granite areas , 35 

Phillips Mountain 35 

Powlers Mountain 35 

Area of porphyritic granite 35 

Basic rocks . 35 

Guilford County 35 

The McLeansville quarry 35 

The Guil quarry 36 

The Jamestown quarry 36 

The High Point quarry ___ 37 

The Buchanan quarry 37 

The Pearman quarry 37 

Other granite areas 37 

Browns Summit and vicinity 37 

Summerfield and vicinity 38 

Greensboro area 38 

Basic rocks , 38 

Forsyth County 38 

The Piedmont quarry _-_ 38 

Abandoned quarry (Piedmont) 39 

Snyder property 39 

The W. E. Graham quarry 40 

Basic dikes 40 

Caswell County 40 

The Pelham quarry 40 

The State quarry 40 



TABLE OF CONTENTS—CONTINUED 

Page 

Davidson, Iredell, and Davie Counties 41 

State quarry 41 

Mooresville area 41 

Davie County 42 

Basic dikes 42 

Mecklenburg and Cabarrus Counties 42 

Mecklenburg County 42 

The Charlotte area 42 

State quarry 42 

Cabarrus County .-.__ 42 

Basic rocks 43 

Gaston, Lincoln and Catawba Counties 43 

Other counties 43 

Alamance County 44 

Person County 44 

Rockingham County 44 

Granites of the Western Piedmont 44 

Surry County 45 

The North Carolina Granite Corporation (Mt. Airy quarries) 45 

Other areas *r. 46 

Granites of the Blue Ridge 47 

Swain County 49 

Henderson County 49 

Transylvania County 49 

Clay and Macon Counties : ... 49 

Other areas 49 

Prospecting, exploration, and quarrying 50 

Dimension stone 50 

Prospecting and exploration 50 

Size of deposits 50 

Topography 50 

Joints 50 

Overburden 51 

Color and texture 51 

Quarrying 51 

Removal of stone from quarry 53 

Crushed stone 53 

The testing of granite 54 

Dimension stone 54 

Crushed stone 55 

Hardness 55 

Toughness . 55 

Soundness 55 

Mechanical analysis 56 

Economic aspects . 56 

Economic value 56 

Market value and transportation 56 

Dimension stone 56 

Crushed stone 57 

Production ■.■ 57 

Dimension stone 57 

Crushed stone 58 

Uses 58 

Dimension stone 58 

Crushed stone 58 

Bibliography 59 



VI 



FIGURES 

Page 
Figure 1. Lassiter quarry, Rolesville, Wake County 19 

2. Paving blocks (tube mill liners), Balfour quarry, Rowan 
County 29 

3. Principal quarry of Salisbury Granite Industries, Inc., 
Rowan County 32 

4. Cutting granite with diamond saws, Mt. Airy quarries, 
Surry County 46 

5. Idealized cross-section of pit and bench-type quarries 50 

6. Plug and feather splitting of granite, J. A. Logan Granite 
Company, Rowan County 52 

7. Channel bar in working position, the J. A. Logan Granite 
Company, Rowan County 52 

8. Value of granite in North Carolina, 1901-1950 57 



PLATES 

Plate I. Generalized geologic map of North Carolina 7 

II. Location map, Northeast Piedmont and parts of the Coastal 

Plain 15 

III. Location map, Central Piedmont 27 

IV. Location map, Western Piedmont and Blue Ridge 48 



TABLES 

Table I. Composition of granite and related rocks 1 

II. Principal producers of granite in North Carolina 9 

III. Results of Los Angeles abrasion tests on some North Caro- 
lina granites 55 

IV. A percentage relationship of granite production to total value 

of minerals produced in North Carolina, 19001950 56 



VII 



Digitized by the Internet Archive 

in 2013 



http://archive.org/details/commercialgranit1954coun 



INTRODUCTION 

The widespread deposits of granite and related crystalline rocks and their utilization in the production 
of various types of crushed and dimension stone constitute a principal mineral industry in North Carolina. 
From a small production prior to 1900, the quarrying and manufacturing of commercial granite in North 
Carolina has shown a continued increase, and in 1950 the value of these products amounted to almost one- 
third of the total value of minerals and mineral products marketed in the State. According to the latest 
published figures (U. S. Bureau of Mines, Minerals Yearbook, 1950), the State ranks first in value of mar- 
keted crushed granite and seventh in value of dimension granite output. Unpublished figures for 1952 in- 
dicate granite production is still rising in North Carolina. More than 95 percent of the commercial granite 
produced in North Carolina comes from the Piedmont Plateau region of the State; however, large deposits, 
which offer excellent opportunities for commercial use, are available in the Coastal Plain and Blue Ridge 
or Mountain regions. 

Throughout the past half -century of expansion in the stone industry of the State such rock types as 
sandstone, quartzite, slate, marble, and limestone have contributed appreciably to the overall production 
of rock but always have occupied a subordinate position in comparison with the production of granite and 
related rocks. The primary reasons for the predominance of granitic rocks as the largest source of com- 
mercial stone in North Carolina are related to three conditions of occurrence, as follows: (1) Granite exists 
in large volume; (2) the deposits of granite are readily accessible in many localities; and (3) the superior 
quality of granite for use as building stone and crushed aggregate has resulted in a perennial market in the 
State and outlying areas. 

The potential value of the varied stone resources of the State was recognized early, and in 1904 a 
systematic study was begun under the direction of the North Carolina Geological Survey for the purpose of 
evaluating the granite, sandstone, and marble deposits of North Carolina. The subsequent report, based on 
the field and laboratory work done by T. L. Watson and F. B. Laney and titled, "The Building and Orna- 
mental Stones of North Carolina," contains detailed information regarding location, mode of occurrence, 
uses, physical and chemical characteristics of stone deposits of North Carolina, and the extent of their 
utilization. Since its publication in 1906, this report has served as a valuable guide to the stone resources, 
especially granite, in North Carolina; however, it is no longer available for public distribution, and the need 
for a new report of this type is mandatory in the light .of the increased importance and continuing growth 
of the stone industry in the State. Because granite and related crystalline rocks constitute the principal 
commercial stone deposits of North Carolina, this report has as its primary purpose a re-evaluation of the 
granite resources, and it is designed as a guide to the granite industry and the areas of present and poten- 
tial granite production. It contains information pertaining to the economics of rock-quarrying, the origin 
and composition of granite, its physical and structural properties, descriptions of the areas in North Caro- 
lina in which granites occur and are utilized commercially, the principal methods of granite-quarrying, and 
the various methods of testing the durability of both dimension and crushed stone. 

METHODS OF INVESTIGATION AND ACKNOWLEDGMENTS 

The information contained in this report represents the results of fieldwork done intermittently during 
the late summer and early fall of 1952, the winter of 1953, and laboratory work done in the spring of 1953. 
.A large part of the work consisted of visiting the more important operating quarries, a few of the pres- 
ently abandoned quarry localities, and some potential quarry sites. The general characteristics of the rocks 
were studied at the quarries ; quarry superintendents and local inhabitants were consulted concerning the 
production and history of each quarry visited; and representative samples of granite were taken at most 
operating quarries and some potential quarry sites for petrographic analyses. Measurements of the strike 
of the joint systems were made, along with observation of other structural features present in the rock bodies, 
and the size and shape of each quarry visited were noted in order that an estimate could be made of the 
amount of rock removed. Other significant features, such as, thickness of overburden and depth of rock de- 
cay in the quarry areas, were also given attention. The methods of quarrying, transportation facilities, 
and equipment used in cutting or crushing at the quarries were also observed during the field investigation. 
About a third of the fieldwork was devoted to studies of the quarries in Rowan and Surry Counties, where 



/ 
2 The Commercial Granites of North Carolina 

the dimension granite industry of the State is centered. Laboratory work for the report consisted of mega- 
scopic examination of all rock specimens collected and petrographic analyses of the rock types from repre- 
sentative granite areas across the State. 

The fieldwork and compilation of data for this report were done under the direction of Dr. Jasper L. 
Stuckey, State geologist, who also supplied much general information concerning the granites of North 
Carolina. Clifton M. Gibbs, a student at North Carolina State College, ably assisted in the field investiga- 
tion during August and September 1952. Mr. Gibbs also did a large share of the cartographic work accom- 
panying this report. 

Grateful acknowledgments are due Messrs. Hosselton and W. W. Rogers of the J. A. Logan Granite Com- 
pany ; Messrs. W. L. Harris and G. A. McKenzie of the Harris Granite Quarries Company ; Messrs. J. P. 
Frank and John Simmons of the North Carolina Granite Corporation ; Mr. C. R. Deadwyler of the Salisbury 
Granite Industries; Mr. L. M. Seawell of the Piedmont Quarries; and Mr. H. S. Satterwhite of the Bryan 
Rock and Sand Company for their cooperation in familiarizing the author with quarrying operations and 
the general economy of rock-quarrying. The author also wishes to express appreciation for the invaluable 
information supplied by the many quarrymen in North Carolina. Mr. A. C. Dodson, geologist, and Mr. H. F. 
Waller, Sr., laboratory technician, of the Division of Materials and Testing of the North Carolina State 
Highway and Public Works Commission supplied valuable information and test results concerning the test- 
ing of crushed stone from commercial and State quarries in North Carolina. For this information, the 
writer is greatly indebted. The information gathered in the preparation of this report is in some instances 
complemented by various data from the Watson and Laney report of 1906, and many of the petrographic 
descriptions herein were taken from that publication. 

GRANITE DEFINED 

The term granite as used in this report has general reference to very siliceous, massive plutonic rocks. 
In its commercial sense, it includes true granite, granodiorite, quartz-monzonite, and rarely diorite and gab- 
bro. 

Granite as a distinct rock type may be defined as a massive igneous rock of plutonic origin, displaying 
a crystalline texture and containing as essential mineral constituents orthoclase or microclinic feldspar, 
quartz, and one or more dark iron silicate or ferromagnesian minerals, usually biotite or hornblende. Mus- 
covite sometimes occurs with or replaces the ferromagnesian mineral in granite. Most granites also contain 
small amounts of plagioclase feldspar, usually a high-soda variety (albite, oligoclase), and a more or less 
uniform distribution of one or more of the principal accessory minerals : epidote, magnetite, hematite, zir- 
con, apatite, titanite, pyrite, and garnet. The averages of the principal minerals composing samples of 
granite from many localities are shown in column 5 of Table I. In instances where the mineral composition 
of the rock in a particular deposit fails to conform with the general average but has the appearance of 
normal granite (biotite granite), it is referred to in this report as granite or granitic rock, and a clarification 
of the general term is made in the petrographic descriptions. 

Many of the so-called granites of North Carolina approach more closely the mineral composition of 
granodiorite and/or quartz-monzonite than normal granite. Such rocks differ from normal granite only in 
containing an excess of plagioclase feldspar and a corresponding decrease in potash feldspar. For example, 
granodiorite may be designated as a granite containing an excess of plagioclase over orthoclase and micro- 
cline with normal amounts of quartz and biotite or hornblende. Quartz-monzonite contains in essentially 
equal proportions plagioclase and orthoclase feldspar, together with quartz and biotite or hornblende. An- 
other related rock found somewhat extensively in the central section of the State is termed syenite. Like 
the aforementioned types, it is genetically and texturally related and in many ways is like granite in chem- 
ical composition. These more or less acid siliceous rocks are often in complex arrangement with diorite and 
gabbro types of similar texture and occurrence, and in such areas the term "granite-diorite complex" is used 
to indicate the complex arrangement of rock types. Rocks in which the growth of certain mineral constit- 
uents is roughly parallel may also contain mineral percentages comparable to the massive plutonic rocks and 
are usually termed gneissic-granite, gneissic-granodiorite, or granite-gneiss. Commonly, it is the biotite or 
hornblende constituent of gneissic rocks which displays a marked parallelism. Table I lists the chemical 



The Commercial Granites of North Carolina ?, 

composition of several North Carolina granites and related rocks, together with the chemical composition 
and average mineral percentages of the principal rock types. 



Table I. Composition of Granite and Related Rocks 

2 3 4 5 6 





Granite 

Near 

Raleigh 

Wake 

County 

Percentage 


Granite 
Near 

Mooresville 
Iredell 
County 

Percentage 


Granite 
Dunns 

Mountain 
Rowan 
County 

Percentage 


Granite 

Near 

Mt. Airy 

Surry 

County 

Percentage 


Granite 

Average 

of 

23* 

Percentage 


Syenite 

Average 

of 

50** 

Percentage 


Diorite 

Average 

of 

IJQ** 

Percentage 


Gabbro 

Average 

of 

24** 

Percentage 


SiC-2 


69.28 
17.44 
1.08 
1.22 
0.16 
0.27 
2.20 
3.64 
2.76 


66.01 

17.44 

5.62 


75.14 
16.10 


70.70 

16.50 

2.34 


69.35 
14.27 
1 .22 
2.33 
0.07 
1.13 
2.18 
2.98 
5.36 


60.19 
16.28 
2.74 
3.28 
0.14 
2.49 
4.30 
3.98 
4.48 


56.77 
16.67 
3.16 
4.40 
0.13 
4.17 
6.74 
3.39 
2.12 


49.50 


Al 2 Os 


18.00 


Fe 2 3 


2.80 


FeO 




5.80 


MnO 


0.23 
1.44 
1.11 
5.06 
3.16 


Trace 
0.04 
0.93 

5.82 
2.57 




0.12 


MgO. _ 


0.29 
2.96 
4.56 
2.45 


6.62 


CaO 


10.64 


Na 2 


2.82 


K 2 


0.98 


Total 


98.05 


100 .07 


100.60 


98.80 


98.89 


97.88 


97 .55 


97.28 






Average Quart: 
Average Orthot 
Average Plagio 
Average Mafia 


,*** 








30.00 
45.00 
15.00 
10.00 








dase*** 








60.00 
20.00 
20.00 






clase***._ 








65.00 
35.00 


55.00 


s and Others*** 








45.00 











* Modified after Johannsen 
** Modified after Daly 
*** Modified after Grout 

ORIGIN OF GRANITE 

Granites and related rocks are considered in this report as a solidified magma derivative, emplaced 
into the crustal portions of the earth while in a viscose liquid or plastic condition. This magma is a siliceous 
rock-melt, differentiated by simple density relationships from a subcrustal reservoir of magma in which the 
essential mineral components of granite crystallize in a complex but orderly fashion. Many of the crystal- 
line rock bodies in the granite areas of the world owe their existence to the solidification of silica-rich mag- 
mas within the crustal portions of the earth ; however, in recent years much controversy has centered around 
the purported metasomatic or metamorphic origin of granite, processes whereby pre-existing rocks, com- 
monly sedimentary rocks, are changed in place to granitic rocks by metasomatic enrichment or solution pri- 
vation, accompanied by recrystallization or by recrystallization under stress and without additions from 
sources outside the rock. These alteration processes, known as "granitization," are today widely accepted 
as the origin of some massive crystalline as well as gneissic rocks of granitic composition. Granites formed 
by both processes are present in North Carolina, but the relationship of the granite deposits to the adjacent 
rocks is extremely complex, and no attempt was made during the investigation to differentiate between 
"metamorphic granites" and igneous granite. However, the author is confident that such a separation can 
be accomplished by an intensive field and petrographic study of the massive crystalline rocks and the granite 
gneisses of the State that seem most likely to have had a primary sedimentary or previous basic igneous 
or metamorphic origin. 

DIKES PENETRATING THE GRANITES 

Throughout the granite areas of the State, dike materials of several different types have wide distribu- 
tion. The types included in the intrusives are acid and basic dikes* and mineral veins, which range in tex- 



* Author's Note: Acid dikes are composed largely of potash feldspar, quartz and subordinate amounts of mafic, or iron mag- 
nesium silicates. Basic dikes are composed of mafic and femic minerals, plagioclase, subordinate accessories, and little or no 
quartz. 



4 The Commercial Granites of North Carolina 

ture from that of quartz veins through aplitic, granitoid, pegmatitic, and diabasic, with many of the basic 
dikes bearing a notable schistose structure. The dikes and veins may vary from an inch to several hundred 
feet in width and show great variation in strike direction. 

Acid Dikes and Veins: In the granite areas of the State, veins and dikes of acid composition are dis- 
tributed rather uniformly, and in some localized areas they constitute the major rock material. The dikes 
and veins range from pegmatitic to aplitic and in a few instances to a granitoid texture but are alike in a 
composition in which quartz and feldspar predominate, with more or less biotite as an accessory mineral. 
Pegmatite dikes are common, occurring in many of the granite areas and in some of the quarries. They are 
composed of white or pink feldspar and quartz grains, ranging from an inch to more than three inches across, 
which commonly display complex intergrowth. In most of the dikes, small plates of biotite or muscovite are 
found in minor amounts, and occasionally one or more granite accessory minerals are present. 

Aplite dikes of exceedingly fine-grained to almost cryptocrystalline texture occur in many granite areas 
but are far less common than pegmatite. The most notable localities in which aplite occurs are Wake Coun- 
ty, in the areas underlain by granite gneiss, and in northern Alamance County. Few were observed else- 
where. In composition, the aplite dikes are remarkably similar to the enclosing granite but generally con- 
tain little, if any, plagioclase. According to Watson and Laney, most aplites in the granite areas of the 
State should be placed with the "potash aplites." In size, the aplites range from less than one-half inch to 
about six inches in width and, so far as observed, occur entirely as dikes. 

The presence of granitoid dikes in the granite areas of the State is comparable in occurrence to the peg- 
matite but are less abundant. Often associated with pegmatites, these dikes are distinguished by a smaller 
and more uniform grain size and sometimes by the conspicuous absence of micaceous or platy minerals, 
giving a binary or two-mineral granite. The size of these intrusives is varied, ranging from an inch to sev- 
eral feet in width. As a rule, the smaller dikes are composed of binary granite and are found throughout 
the granite areas, while the larger normal granite types are restricted more or less to certain localities in 
the Central Piedmont and are most abundant in the granite-gabbro-diorite complex. They can be seen pene- 
trating both the granite and the gabbro-diorite and are most prevalent in contact zones. 

Quartz veins are a common sight in the granite areas and usually show strongest development in the 
areas of pegmatitic intrusion. So far as determined, the quartz is restricted largely to joint and other open- 
fracture filling but occasionally occurs as "pseudo-veins," formed by the segregation of silica at the time 
of the crystallization of the granite magma. The veins range in width from knife-edge to large fissure veins 
10 or more feet across and, like the pegmatites, are rather uniformly distributed through the granite areas 
of the State. 

Basic Dikes: The most striking rocks intruding the granite consist of diabasic and schistose dikes of 
basic composition. Ranging in width from several inches to several hundred feet, the dikes are found in 
increasing numbers from the Coastal Plain westward into the Piedmont. 

Schistose Dikes : This schistosity is developed parallel to the direction of strike and normal to any gneissic 
structure in the granite. Contacts with the country rock are sharp. In all localities observed, the basic dikes 
cut the quartz veins, which are assumed to coincide with the later phases of granite intrusion. The schistose 
dikes, which are most prevalent in the Central Piedmont, are various shades of dark green and are moderately 
to highly decomposed. According to Watson and Laney, the principal mineral constituent of the dikes is 
hornblende; however, it is likely that both amphiboles and pyroxenes are contained in the composition. The 
dikes paralleling the major joint systems in the granite usually show a marked schistosity in the contact 
zone with the country rock. 

Diabase Dikes: In many localities and often proximately associated with basic schistose dikes are more 
or less massive diabase dikes of gabbro composition, which, like the schistose variety, seem to increase in 
number westward from the fall line to the Piedmont. Orientation of strike direction can be correlated rough- 
ly with principal jointing in the granite. In most localities, weathering of the dike material is in an advanc- 
ed stage, and decomposition has imparted a light- to dark-brownish color to the dikes. In a few instances the 
decay is reddish brown. 



V 



The Commercial Granites of North Carolina 5 

PHYSICAL AND STRUCTURAL PROPERTIES OF GRANITE 

DIMENSION STONE 

General: The availability of granite for fine building and monumental purposes is dependent upon varied 
factors responsible for its physical makeup, such as, resistance to weathering, desirable color, uniform tex- 
ture, an absence of injurious mineral constituents, and a susceptibility to abrasive polish. The principal fac- 
tors in this determination are: 

Dikes and Veins: The presence of dikes and veins in granite deposits is detrimental to uniformity of the 
quarried stone and in some instances weakens the enclosing rock. Small dikes, veins, and veinlets are often 
found in great numbers in granite deposits and usually render stone useless as a source of commercial dimen- 
sion stone. 

Segregations and Inclusions: Mineral segregations and inclusions in granite deposits tend to disturb 
textural uniformity, mar the eye appeal of the finished product, and resist polish. The excessive segrega- 
tion of biotite, muscovite, and amphiboles is quite common in granitic rocks and should be avoided when 
dimension stone of high quality is desired. Occasional small segregations of micaceous or platy minerals do 
not detract from the beauty of the stone, nor do they affect the ability to take abrasive polish. 

Texture : Texture in igneous rocks has reference to individual grain size and fabric within a given in- 
trusive mass and is perhaps the principal requisite of stone for use in building and ornamental work. Tex- 
ture in the granites and related rocks ranges from aplitic, through fine-grained, medium-grained, large- 
grained, to porphyritic, all of which may or may not show fabric or a systematic arrangement of individual 
mineral grains. Textures result from several factors' influencing the change of a magma from a liquid or 
plastic state to a consolidated mass. These factors, in order of general importance are rate of cooling, press- 
ure, and the presence of mineralizers. In general, rapidly-cooling magmas tend to form rocks of fine-grained 
size and uniform texture ; whereas, under similar pressure conditions, slow-cooling masses form rocks made 
up of large grains of irregular size. That pressure indirectly influences texture is well agreed upon, but the 
degree of influence is purely theoretical. The gases held in solution under pressure are responsible for certain 
controls, since it is believed that gases dissolved in magmatic water (mineralizers) control the viscosity of 
the magma. With the partial release of pressure, the gases volatilize, remain in the rock-melt, and appar- 
ently reduce the viscosity of the magma, thus permitting a more rapid diffusion and subsequent growth of 
larger crystals to produce a porphyritic or large-grained rock. If pressures on the crystallizing magma are 
absent, the gases escape rapidly and a rock of finer texture results. Intermediate conditions undoubtedly 
exist, so that, many grain sizes are possible, depending on differences in pressure and the consequent volume 
of mineralizers allowed to remain in the rock melt. In addition to the normal functions in the granite magma, 
the escaping of the mineralizers is probably instrumental in the extension of a granite body by gaseous liquid 
assimilation or granitization of the surrounding older rocks. The principal grain sizes or textures reflecting 
pressure and relative temperature present during the solidification of granite magma fall into four general 
classes : 

(1) Granite porphyry, or very coarse-grained granite, is composed of mineral grains more than one inch 
across. The feldspars are most frequently the largest grains in granite porphyries and usually show complex 
intergrowth with large quartz grains, as in graphic granite and alaskite. The common accessory minerals — 
biotite, muscovite, and hornblende — generally remain considerably smaller than either feldspar or quartz; 
however, they may grow comparatively large, perhaps one or more inches across. Such occurrences of mus- 
covite are found in the "alaskite" bodies in Western North Carolina. In some instances granite porphyries 
are quarried as dimension stone, but no rocks of this texture are known to be worked for this purpose in North 
Carolina. 

(2) Large-grained granite consists of mineral grains one-half to one inch across. In the case of a granite 
of this texture, the feldspars also constitute the largest grain size and the accessory minerals, the smallest. 

(3) Medium textures or even-granular granites are in greatest demand in the building and ornamental 
trade and may be considered to include those stones with individual mineral grains ranging from one twenty- 
fifth to one-half inch across. Smaller grains may exist within the rock in a subsidiary amount, acting as a 



6 The Commercial Granites of North Carolina 

groundmass for the larger grains, but generally constitute a very small fraction of the total volume of the 
rock. 

(4) Fine-grained granite is composed of mineral grains less than one twenty-fifth of an inch across and 
usually shows an even-granular texture. 

Rift and Grain : Because granite is the hardest natural building stone and the most expensive to quarry 
and shape into a usable form, it is usual, preceding and during quarrying operations for dimension stone, to 
consider the two physical properties known in the quarrying industry as rift and grain. Rift is the direction 
along which the artificial fracturing of granite can be accomplished with greatest ease, and grain is a second 
direction of splitting, less strongly marked and usually at right angles to the rift. Both may be considered 
as obscure foliation of microscopic dimension, on the order of 0.09 mm. to 0.13 mm. in width. Rift and grain 
permit straight and relatively smooth breaks in the rock and add facility in quarrying and finishing methods. 

The origin of rift and grain is obscure, although according to Dale (Dale, T. N., 1923) the two "fracture 
systems" result largely from the orientation or lining-up of the mineral constituents of the rock (primary or 
secondary foliation). However, rift and grain in granitic rocks may also result from the parallelism of 
cleavage directions of the minerals, by incipient or microscopic jointing caused by internal or external forces 
acting upon the intrusion, or by a parallel arrangement of fluidal cavities present in the quartz grains. 

Sheeting: The vertical thickness of dimension granite is dependent upon either a natural or artificially- 
produced plane, running approximately parallel to the surface of the deposit and in essence dividing the body 
into sheets or layers of near-uniform thickness. The thickness of the sheeting plane (bottom joints) varies 
considerably from quarry to quarry, often being from 1 to 10 feet or more in dimension, and generally in- 
creases with depth. Natural sheeting planes, like rift and grain, are obscure as to origin ; however, Dale con- 
siders in some detail most of the theories advanced concerning their origin and concludes their existence is 
primarily the result of the release of compressive strain. Sheeting is considered by the writer as the result 
of a progressive release of compressive strain during the erosion of overlying material, coupled with the 
expansion of the mineral constituents of the granite in response to solar heat. Sheeting, although not al- 
ways present in plutonic rocks, is present in most commercial granite areas in North Carolina. The notable 
exceptions are the Mt. Airy district in Surry County and the Salisbury area of Rowan County, where arti- 
ficial induction of sheeting is necessary for the successful quarrying of dimension stone of uniform thickness. 
A description of this method is presented in the section on quarrying. 

Color: Uniformity of color over a large areal extent is a desirable feature in the marketing of granite 
for use in building and ornamental work. If colors are consistent, granite from a certain locality becomes 
famous through the years, and the demand for the stone continues to increase. The colors in granite are in 
large part dependent upon the intensity of chroma of the predominant feldspar, although mafic minerals, 
tinted muscovite, and quartz may contribute appreciably to the overall color of a stone. Characteristic colors 
are red, pink, gray, and "white." Granite deposits generally display a variety of colors. 

Joints: Most granitic masses are traversed by one or more sets of vertical or nearly vertical joints, re- 
ferred to as the "major systems" and the "secondary systems." The major system consists of two planes 
of jointing which intersect at or near 90 degrees and are usually accompanied by one or more secondary sets 
which form a junction at an angle more or less than 90 degrees. It is believed that these systems result from 
compressive or torsional strain, resolved into two components, each at an angle of 45 degrees with the strain- 
ing force. 

CRUSHED STONE 

General: The physical and structural properties of stone for crushing are important considerations in 
both the quarrying procedures desired and the ultimate use to which it will be put. Toughness and hardness 
of the rock influence the cost of production, and the soundness of stone determines its fitness for general use. 

Toughness and Hardness : The toughness of a stone is a measure of its resistance to impact, and hard- 
ness is a property based upon resistance to surface abrasion. Both of the properties are determined by the 
individual mineral percentages, the degree of weathering, the texture, and the fabric of the rock. The test- 
ing and determination of both these properties is accomplished in various ways, some of which will be dis- 
cussed in a subsequent section. 



The Commercial Granites of North Carolina 



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8 The Commercial Granites of North Carolina 

Soundness : The soundness of crushed stone has reference to its resistance to weathering, more specific- 
ally, its resistance to deterioration resulting from repeated freezing and thawing. The rapidity of disinte- 
gration of stone subjected to freezing and thawing is dependent upon several factors resulting from its 
physical and chemical makeup. They are the number and size of microscopic pore spaces, or interior voids, 
and their susceptibility to filling by water. Numerous tests, none of them standardized, have been devised 
for the acceleration and measurement of resistance to freezing and thawing, one of which will be discussed 
in the section concerned with the testing of granite. 

Structurally, granitic bodies utilized in the production of crushed stone need not meet the rigid re- 
quirements necessary in dimension-stone quarrying. Joint planes may be prevalent, closely spaced, and in 
complex arrangement within the rock mass. Color, texture, segregations, and inclusions are normally of 
little or no significance. 

GEOGRAPHIC DISTRIBUTION OF GRANITE AND RELATED ROCKS 

Granites and related rocks in North Carolina crop out or lie at shallow depths over approximately one- 
fifth of the total area of the State ; however, the area of present, past, or potential productivity is consider- 
ably smaller. In much of the area of occurrence, granitic rocks lie below a thick mantle of residual decay, 
but in some localities the mantle is thin or absent and the rock sound. Even in some of these localities, 
shallow-lying or exposed rock may be weathered sufficiently to render it unsuitable for commercial uses 
prior to the removal of partially decayed granite or sap rock. The area in which granites and related rocks 
are present in North Carolina is divided geographically into the three major physiographic provinces of the 
State, namely, the Blue Ridge or Appalachian Mountains, the Piedmont Plateau, and the Coastal Plain. This 
physiographic division into provinces is based upon distinct geologic features, in the order of their impor- 
tance: topography, geologic structure, and lithology. 

Blue Ridge: Eastward from the Tennessee line for distances ranging from 15 to 50 miles lies in the Blue 
Ridge Province, an area characterized by rugged, though somewhat subdued, mountainous terrain and deep, 
constricted valleys, developed predominantly in schists and gneisses of purported pre-Cambrian age. Intru- 
sive granitic rocks of pre-Cambrian and Paleozoic ages are present in many scattered localities. Structurally, 
the rocks are complexly folded into highly contorted and faulted anticlines and synclines within a broad regional 
synclinorium. Thrust faulting is not uncommon. Elevations range from 6,000 feet in the west to a minimum 
of 2,000 feet near the contact with rocks of the Piedmont Plateau to the east. 

Piedmont Plateau: Passing rather abruptly from the eastern limits of the Blue Ridge, the topography 
assumes the less precipitous proportions characteristic of a submontaine or foothill region, in which low 
rounded hills, flat upland divides, and shallow, generally mature, valleys constitute the predominant topo- 
graphic features. The general high-elevation surfaces, attested by the upper surfaces of rounded hills, rep- 
resent remnants of an uplifted peneplane upon which streams flowing consequent and /or subsequent to re- 
gional slope and structure, respectively, have maturely dissected the land surface in cutting to present levels. 
The principal rocks of the Piedmont include pre-Cambrian (?) and late Paleozoic granite and other massive 
crystalline rocks, pre-Cambrian gneisses and schists, and lower Paleozoic meta-volcanics and meta-sediments, 
all of which are more or less structurally related to the rocks of the Blue Ridge. Elevations in the Piedmont 
Plateau range from 300 to 1,500 feet, and the province extends from the Blue Ridge eastward for 150 to 200 
miles to the fall line of the Coastal Plain. 

Coastal Plain: The Atlantic Coastal Plain in North Carolina is physiographically distinguished on the 
basis of the gently dipping, mostly unconsolidated, Cretaceous and Cenozoic marine and continental sediments 
forming an extensive, nearly flat plain, slightly incised by consequent streams. Inliers of meta-volcanics, 
meta-sediments, gneisses, schists, and granitic rocks are fairly common in portions adjacent to the Pied- 
mont. Elevations range from near 400 feet along the fall line to sea level in the east. The maximum width 
is approximately 125 miles. 



The Commercial Granites of North Carolina 9 

Each of the three principal areas is discussed in this report, and for convenience in writing, the State 
is divided, as follows : 

I — Coastal Plain 
II — Piedmont Plateau 

1. Northeast Piedmont 

2. Central Piedmont 

3. Western Piedmont 
III— Blue Ridge. 

Plate I shows the confines of the above areas and the age relations of the principal rock types. It will be 
observed also that the principal occurrences of the granites and related rocks tend to form belts, which trend 
northeast-southwest and essentially parallel the Appalachian Mountains. The greater part of the commer- 
cial granites in North Carolina lies within the confines of the Piedmont Plateau Province, though small work- 
able deposits occur in the western portion of the Coastal Plain and at scattered localities within the Blue Ridge. 

In most of the counties in which granites occur some quarrying operations have been carried out, al- 
though many are quite small and are at present of little or no commercial importance. Only the large opera- 
tions perennially contribute to the total mineral production in the State, the areas of greatest importance 
being: (1) Salisbury, Rowan County; (2) Woodleaf, Rowan County; (3) Mt. Airy, Surry County; (4) Roles- 
ville, Wake County; (5) Sims, Wilson County; (6) Greystone, Vance County; (7) McLeansville, High Point, 
Jamestown, Greensboro, and Stokesdale, Guilford County; (8) Pelham, Caswell County; and, (9) Winston- 
Salem, Forsyth County. Crushed stone is the principal product of seven of the areas listed, and dimension 
stone is the most important product in the Mt. Airy and Salisbury areas. In addition to those listed, many 
quarries are operated on a noncommercial basis by the North Carolina State Highway and Public Works 
Commission for the production of crushed stone for local road and highway maintenance. Table II lists the 
principal producers of granite in North Carolina. 



Table II. Principal Producers of Granite in North Carolina 
Company Principal Product Quarry Location Geographic Division 

Bryan Rock & Sand Co. 

Lassiter Quarry Crushed Stone Rolesville Northeast Piedmont 

Neverson Quarry Crushed Stone Sims Coastal Plain 

Buchanan Stone Co Crushed Stone Greensboro Central Piedmont 

Greystone Granite Quarries Co. 

Greystone Quarry Crushed Stone Greystone Northeast Piedmont 

Harris Granite Quarries Co. 

Balfour Quarry Dimension Stone Granite Quarry Central Piedmont 

Carolina Quarry Dimension Stone Granite Quarry Central Piedmont 

J. A. Logan Granite Co. 

Faith Quarry Dimension Stone Faith Central Piedmont 

Lambert Brothers, Inc. 

Pelham Quarry Crushed Stone Pelham Central Piedmont 

North Carolina Granite Corp. 

Mt. Airy Quarries Dimension Stone Mt. Airy Western Piedmont 

Piedmont Quarries Co. 

■ Winston-Salem Quarry Crushed Stone Winston-Salem Central Piedmont 

Guil Quarry Crushed Stone Stokesdale Central Piedmont 

Salisbury Granite Industries, Inc. 

Collins-Durax Quarries ...Dimension Stone Granite Quarry Central Piedmont 

Superior Stone Company 

McLeansville Quarry Crushed Stone McLeansville Central Piedmont 

Woodleaf Quarry Crushed Stone Woodleaf Central Piedmont 

Whitlow Brothers 

High Point Quarry Crushed Stone High Point Central Piedmont 

CCC Quarry Crushed Stone Jamestown Central Piedmont 

State of North Carolina Crushed Stone Various Localities All Divisions 

( Noncommercial ) 



10 The Commercial Granites of North Carolina 

GRANITES OF THE COASTAL PLAIN 

The Coastal Plain Province of North Carolina covers approximately two-fifths of the area of the State 
and includes 45 counties. The geographic separation of this province from the adjacent Piedmont is based 
on several prominent geologic features previously discussed and shown on Plate I. , The line dividing the 
Coastal Plain from the Piedmont is hypothetical, in that it marks approximately the present westward ex- 
tent in the State of sedimentary sands and clays belonging to the Coastal-Plain formations. It is known 
that the Cretaceous and younger sediments of the Coastal Plain unconformably overlie metamorphosed, slaty 
volcanic and sedimentary rocks and granites. Drilling logs from unpublished reports of oil exploration 
wells on the Coastal Plain report granite or slate as the basement rock, the granite being considered the 
younger rock because of similar types known to intrude rocks of the Volcanic-Slate Series in the Northeast 
Piedmont. The relatively small outcrops of granite within the Coastal Plain of North Carolina, therefore, 
represent inliers of the extensive subsurface crystalline rocks from which thin, loosely consolidated sedi- 
ments have been eroded. The stripping of the Coastal-Plain sediments from the granites has taken place 
largely in areas adjacent to the major streams and their principal tributaries, near the contact with rocks 
of the Piedmont Plateau. Most of the outcrops in these areas tend to form elongated masses of ledge-like 
and boulder form and in cases where the outcrop is back from the stream, low, flat, or dome-like bodies. 

The principal granite areas are found in Wilson, Edgecombe, Nash, Pitt, Anson, and Richmond Coun- 
ties. In only one of these areas — at Sims in Wilson County — is granite being produced commercially; how- 
ever, other deposits may merit investigation as future sources, especially in the Wadesboro-Rockingham 
area of Anson and Richmond Counties and around Rocky Mount in Edgecombe County. In almost all of the 
areas of fresh outcrop in the Coastal Plain, more or less systematic quarrying for dimension stone was done 
in the past, but it is doubtful that the rock in many of these areas will be utilized further. 

WILSON COUNTY 

With the exception of a few small areas, the entire central and eastern parts of Wilson County are cov- 
ered by a thin veneer of Coastal-Plain sediments, overlying granite, volcanic slates, gneisses, and schists. 
The western portion of the county lies within the eastern prong of the Volcanic-Slate Series, but in a few 
localities granite has penetrated these older rocks and crops out at the surface as low dome-like masses. 

CONTENTNEA CREEK AREA 

About two miles south of Wilson on U. S. Highway 301, fresh granite is exposed through the sediments 
on both sides of Contentnea Creek for several miles upstream and along the adjacent areas a short distance 
back from the stream. The granite occurs as large boulders in the stream and as flat-surface masses in 
adjacent areas. It is a uniformly coarse-grained rock of dull pinkish-red color, becoming porphyritic in 
some places. Feldspar is the predominant mineral constituent of the granite, composing about 80 percent 
of the total volume, while quartz constitutes approximately 15 percent. Biotite, largely altered to chlorite, 
and a very small amount of apatite make up the remainder of the rock. Three sets of joints separate the 
granite into blocks of various sizes, striking almost N., N. 65° W., and N. 50° E. None of the joints are 
filled with vein or dike materials. Watson and Laney describe a section of the rock petrographically, as 
follows : 

"Plagioclase nearly equals in amount the potash feldspar, which consists mostly of orthoclase 
though some microcline occurs. Plagioclase is in very large laths, finely striated and corresponds 
in physical properties to albite. The feldspars are extensively altered to kaolin and muscovite. . . . 
Quartz is in very large grains interlocking with the feldspar and will probably not exceed 15 per- 
cent of the entire rock." 

The rock falls into the type defined by mineral composition as quartz-monzonite. The rock is of good qual 
ity and appearance but is poorly situated for utilization as commercial stone. 

SIMS AREA 

This area contains a small body of granite, forming the main deposit on which the Neverson Quarry 
is located. It lies about one mile west of Sims along U. S. Highway 301 and immediately adjacent to the 






The Commercial Granites of North Carolina 11 

Norfolk and Southern Railway. Though the area lies outside the Coastal Plain, it is discussed here because 
of close proximity to the fall line and further because it is located within a county lying partly within 
the Coastal Plain Province. The deposit is a conspicuous dome-like outcrop, covered in most places by 5 
to 40 feet of reddish-pink to buff colored granite residuum, which contains a few boulders of exfoliation. 
The rock body is moderately sheared, but only two prominent planes of jointing were detected. The strikes 
of these joints were measured as N. and N. 65° E. Evidence of shear is especially prevalent in the rocks 
forming the west perimeter of the roughly circular pit quarry, the granite appearing badly mashed and brok- 
en and the joint systems hardly detectable. (For quarry type, see page 50.) 

The rock is a medium-grained, pinkish-gray granite, containing abundant orthoclase, smoky quartz, 
and minor amounts of biotite and pyrite. In some places in the quarry, notably the highly sheared parts, a 
thin veneer of epidote coats the joint surfaces and in some instances replaces the pink feldspar. Many inter- 
growths of orthoclase and quartz can be seen in a hand specimen of the rock. This renders toughness to 
the rock, making it an excellent crushed product for road surfacing and concrete aggregate. Results of 
Los Angeles abrasion tests on the stone are shown in Table III, page 55. A petrographic analysis of granite 
from the Neverson Quarry by the U. S. Bureau of Public Roads shows the following minerals and their per- 
centages : 

Quartz 39% 

Orthoclase 55% 

Biotite : 4% 

Calcite '. 1% 

Apatite 0.6% 

Muscovite 0.4 % 

According to this thin-section analysis, the Neverson Quarry rock is a normal or biotite granite, which has 
been subjected to mineral enrichment by thermal waters or normal near-surface ground waters. The altera- 
tion is made apparent by the presence of calcite, a mineral not associated with the crystallization of silicic 
magmas. The pyrite and epidote are also of secondary origin. 

The Neverson Quarry was first opened in 1917 for the production of road metal and jetty stone and 
continued in operation until it was closed in 1927. Production was resumed for about one year between 
1938 and 1939, but the quarry was closed again and was not reopened until 1940, from which time pro- 
duction has continued and enlarged to the present day. The principal products from the quarry, in order of 
general importance, are concrete aggregate, road metal, and railroad ballast. Crushed material from the 
quarry is shipped by rail to many cities in the Coastal Plain and is reported to be a chief source of stone 
received in Norfolk, Virginia. 

ELM CITY AREA 

The Elm City granite area includes about 15 to 20 acres of boulder outcrops and nearly flat surface 
masses of granite, two miles NNE. of the town of Elm City and along the Atlantic Coast Line Railroad. In 
the approximate center of the area of outcrop, quarrying of the granite has been carried on intermittently 
for almost a hundred years. The extereme toughness and apparent hardness of granite from this deposit 
dismisses it from consideration as an economically available source either of crushed or dimension stone. 
No quarrying has been done at the locality in more than 30 years ; however, in the past the quarry furnished 
crushed stone to Coastal-Plain cities in North Carolina. The quarry area covers approximately 400 by 
600 feet and is reported to be more than 30 feet in depth. It is partially filled with water. Fresh granite 
lies below 1 to 30 feet of reddish-tan, clayey residuum, below which exfoliation of the granite is common. 
The massive rock is cut by two prominent but widely spaced sets of joints, striking N. 75° W. and N. 40° E., 
and in many places the open fractures have been filled with quartz, coarse feldspathic material, or greenish 
schistose dike material composed largely of amphibole and quartz. Small cubes of pyrite are disseminated 
through the dike material and the granite. The unfilled joints and fractures are slickensided, and in some 
places a thin coating of a yellowish-green mineral, probably damourite (hydro-muscovite), is present on 
the surfaces. 

The rock is light pinkish-gray, medium-grained, and is composed of closely interlocked grains of quartz 
and feldspar and a little biotite. The principal accessory minerals include zircon, apatite, ilmenite, and 



12 The Commercial Granites of North Carolina 

titanite. The stone is very hard and is reported to possess poor working qualities. A thin section of the 
granite is described by Watson and Laney, as follows : 

"... a biotite granite . . . scattered occasional and partially idiomorphic crystals of compact horn- 
blende. Feldspar preponderates and is composed of the potash varieties with much striated acid 
plagioclase ... of the composition Abi 2 Ant. The feldspars are clouded from slight alteration into 
kaolin and muscovite . . . Quartz forms distinct areas of an interlocking mosaic of smaller grains 
than the feldspar through which are scattered occasional feldspar grains and biotite. Biotite is 
altered to chlorite." 

From the above description, which lacks definite percentage relations, the rock probably should be placed 
in the type previously defined as granodiorite ; the rock, however, may represent an example of quartz-mon- 
zonite. 

EDGECOMBE AND NASH COUNTIES 

In only a small area in Edgecombe County, located near the Nash County line, do granite and older 
rocks crop out above the Coastal-Plain sediments. To the west, in Nash County, granite and volcanic slates 
occupy the entire area with the exception of two narrow strips of sediments to the north and south, re- 
spectively, in the eastern portion of the county. Nash County is discussed with the Coastal-Plain counties 
because of the relation and continuity of the outcrops, beginning in western Edgecombe County and continu- 
ing westward along the Tar River into Nash. Large boulder outcrops of granite first appear about one-half 
mile north of Rocky Mount, in Edgecombe County along U. S. Highway 301, continue northward for approx- 
imately one-half mile, and are best exposed on both sides of the Tar River near the junction of N. C. High- 
way 43 and Highway 301. Westward from this junction, the granite is traced for several miles into Nash 
County by small boulder or flat-surface outcrops. The exposures in the area described merit investigation 
as a possible source of stone for crushing. In this area, granite has intruded schist and gneiss. The out- 
crops of granite in the river and along its banks near the highway junction were examined and found to 
consist of pink and gray feldspar, quartz, and fine books of biotite. The texture of the granite varies from 
fine to large and to porphyritic, but in all size phases the rock is even-granular and is a light pinkish-gray. 
Segregations of quartz are present in some of the outcrops. The outcrops are generally fresh and firm, 
though some of the boulder-like exposures show exfoliation. Four sets of joints, cutting the rock into blocks 
of various sizes, strike N., N. 40° E., N. 30° W., and N. 75° W. and in some places are very closely spaced. 
Vein material, consisting of quartz and fine-grained pegmatite, occupies some of the joints. The following 
petrographic description of the stone was taken from the Watson and Laney report : 

". . . closely interlocked aggregate of feldspar, quartz, and biotite. Orthoclase and microcline have 
about equal distribution through the section with but little plagioclase indicated. . . . Biotite . . . 
is partly altered to chlorite. ... A few scattered grains of black iron oxide and inclusions of pris- 
matic apatite and zircon complete the list of minerals in the rock." 

The rock is a normal or biotite granite. 

PITT COUNTY 

With the exception of a small area near Fountain in the extreme western portion, where granite gneiss 
is exposed, Pitt County is covered entirely by Coastal-Plain sediments. The occurrence of granite in Pitt 
County is discussed briefly here because it represents the easternmost appearance in the Coastal Plain of a 
granite or related rock, not because of any particular commercial possibilities offered by the rock. 

FOUNTAIN AREA 

The area of outcrop lies just outside the southern corporate limits of Fountain and consist of 2 or 3 acres 
of nearly flat surface outcrops of a gneissoid rock of granitic composition. The unweathered rock is an ex- 
tremely tough (hard), massive granite, containing dark-colored gneissic inclusions and a few widely spaced, 
mineral-filled joints, which strike approximately N. and E. The joints are filled with one- to two-inch veins 
of milky quartz, containing in some places a little feldspar. The inclusions range from one-fourth of an 
inch to more than 2 feet across and are quite prevalent in some parts of the deposit. The residual overbur- 
den consists of about two inches of yellowish-brown, gritty clay. Bottom joints in the rock are well devel- 



The Commercial Granites of North Carolina 13 

oped and cut the deposits into sheets 6 to 18 inches in thickness. A small amount of dimension stone was 
removed from this deposit for local use as late as 1938, and it is reported to work very poorly and with great 
difficulty. Although the stone is a pleasing light gray color, it is doubtful that it will be of commercial use 
because of the extreme toughness and lack of workability. 

Megascopically, the rock is a highly siliceous, medium-grained granite-gneiss, containing quartz, feld- 
spar, biotite, and iron oxide. A thin section of the rock shows the following mineral composition : 

Quartz 36 % 

Orthoclase (much microcline) 47% 

Plagioclase 5% 

Biotite hornblende 9% 

Other (magnetite, apatite, chlorite, caicite) 3% 

According to the analysis, this stone falls into the gneissic-granite class as previously denned. 

ANSON AND RICHMOND COUNTIES 
THE WADESBORO-ROCKINGHAM AREA 

The Wadesboro-Rockingham granite area extends from about two miles west of Rockingham, in Rich- 
mond County, westward to within three miles of Wadesboro, in -Anson County. Although outcrops of fresh 
granite are rather rare, the presence of extensive deposits lying beneath granite residuum is recognized 
by the color and partially decayed mineral components of the residual material. In many places Coastal- 
Plain sediments overlie the granite or its disintegrated product, but in general these deposits are spotty. 

Granite showing the least degree of weathering is exposed best along and immediately south of the 
Seaboard Air Line Railroad, beginning about 2.5 miles west of Rockingham and appearing in the deeper 
cuts almost to Wadesboro. In some of the cuts, the granite is essentially fresh, while in others the effects 
of weathering have rendered the rock unsuitable for commercial use. Other exposures of interest can be 
seen in the deeper cuts along U. S. Highway 74, west of Rockingham, and in the vicinity of Lilesville and 
Bonsai, about 4 miles east of Wadesboro. These exposures are moderately to strongly weathered and ap- 
pear as bed-like ledges on both sides of the highway. Complete decay has progressed to great depth along 
the fractures cutting the deposit and to an overall depth of about 15 feet in the massive portions of the 
deposit. Fresh outcrops of granite appear over a rather extensive area south of the railroad and west of 
the Pee Dee River. Irregular patches of Coastal-Plain sediments cover the granite in many parts of this 
area ; however, boulders and ledge-like and flat-surface masses of granite are quite numerous in other locales 
within the same area. Prominent flat-surface and boulder outcrops of fresh granite can be seen along U. S. 
Highway 52, beginning about 2 miles south of Wadesboro. Jointed structure is well developed in the gran- 
ite exposures of the area and is generally spaced so as to subdivide the deposit into blocks of large dimension. 
Measurements of the joints show the following strikes : Bonsai area, N. 70° E., N. 20° W., and N. ; south of 
Wadesboro, N. 30° E. and N. 60° W. 

The granite in the Wadesboro-Rockingham area is fairly uniform both in texture and color, generally 
being of large to porphyritic texture and ranging in color from pinkish gray to light pink. Most color and 
textural combinations produce a pleasing appearance. In none of the outcrop areas visited was a medium- 
grained granite found. In the porphyritic phase, the rock is composed of grains of biotite up to one-fourth 
of an inch across, quartz grains up to three-fourths of an inch across, and feldspars, some of which show 
idiomorphic crystal outline, up to one and one-fourth inches across. In the large-grained phases of the rock, 
the quartz and feldspar grains are about equal in size and the biotite, about half as large. It is interesting 
to note the presence of subrounded quartz grains in some of the outcrops of large-grained granite, their 
presence being especially pronounced in the highly weathered, friable zones. The rocks containing the sub- 
rounded quartz grains noticeably lack idiomorphic feldspars. 

A moderately weathered hand specimen of large-grained material taken from an exposure along U. S. 
Highway 74 near Bonsai has the following mineral composition: 

Orthoclase 30% 

Plagioclase 25% 

Quartz 25% 

Biotite 20% 



14 The Commercial Granites of North Carolina 

A microscopic examination by Watson and Laney of a specimen taken near Rockingham shows the follow- 
ing characteristics : 

". . . an aggregate of quartz and feldspar with considerable biotite. Potash feldspars with nearly 
equal or greater proportion of plagioclase make up the feldspathic constituent, which shows some 
alteration. ... A few scattered grains of magnetite are distributed through the section. . . ." 

On the basis of the incomplete petrographic analysis, the rock of the area should be classified quartz-mon- 
zonite. 

In general, the thick residual material overlying the granite deposits in the Wadesboro-Rockingham 
area, coupled with the availability of gravel from the Coastal-Plain formations, has to a large extent dis- 
couraged the commercial production of granite. This is espescially true in regard to a crushed-stone in- 
dustry, which would be unable to compete with natural gravel production in the area. In most localities 
the initial depth to fresh rock generally constitutes a stripping problem likely to prevent the utilization of 
the granite for dimension stone ; but, despite this problem, the fresh granite is of a good quality and pleasing 
appearance and merits investigation in some areas as a potential source of stone for this purpose. Produc- 
tion in the area has been limited to several small openings near Rockingham for the quarrying of stone for 
local use early in the century. No production is reported from either Anson County or Richmond County at 
present. 

BASIC ROCKS 

The granitic rocks within the Wadesboro-Rockingham area are the first in the granite areas of the State 
to show large-scale penetration by basic-rock dikes of either a diabasic texture or schistose structure. As 
will be noted later, dikes of this character are quite prevalent in the Piedmont section of the State but up to 
this point are found sparingly on the Coastal Plain. The largest of the dikes in the area is exposed in the 
western part of Rockingham, near the old Great Falls Cotton Mills building on U. S. Highway 74. The 
dike rock is a hard, dense, diabase-like rock, containing much epidote, which imparts a greenish color to the 
rock, and large irregular areas of quartz. According to Watson and Laney, the dike is more than a hundred 
feet wide, strikes about N., and is referred to as a greenstone-diabase dike. Although the Rockingham dike 
is the largest, it is only one of many which outcrop in the area. All are diabasic or schistose and strike 
north or a few degrees west of north. 

GRANITES OF THE PIEDMONT PLATEAU 

The Piedmont Plateau in North Carolina, lying between the Coastal Plain and the Blue Ridge, is second 
in size among the geographic divisions of the State but contains approximately 95 percent of the commer- 
cial granite deposits. The granites in this province have been utilized more or less in both domestic and 
large-scale commercial production for more than a hundred years, and the dimension granites from this 
region have, since 1900, been well known throughout the United States and other parts of the world as 
superior quality monumental and building stone. As shown on Plate I, the Piedmont region comprises three 
distinct granite areas : the Northeast Piedmont, the Central Piedmont, and the Western Piedmont. 

Northeast Piedmont: The rocks of the northeastern part of the Piedmont Plateau include several belts 
of granitic rocks, separated by gneisses, schists, and volcanic slates. The granite deposits of the North- 
east Piedmont rank second in volume but last in value of the commercial stone produced in the Piedmont. 

Central Piedmont: The Central Piedmont includes the largest body of granitic rocks in the entire State, 
along with the main belt of the Volcanic-Slate Series and a narrow band of gneisses and schists, all of which 
trend northeast across the State. The granite and related rocks — quartz-monzonite, granodiorite, syenite, 
diorite, and gabbro — occurring in the Central Piedmont comprise the most valuable commercial rock deposits 
in North Carolina. 

Western Piedmont: The Western Piedmont division of the State is underlain largely by gneisses and 
schists, though in certain localities granite has penetrated the older material and outcrops in northeast 
trending belts. In much of the region the granites are gneissic. In volume of commercial granite, the West- 



The Commercial Granites of North Carolina 



15 




LOCATION MAP 

NORTHEAST PIEDMONT 



GRANITE AND RELATED ROCKS 



tt ACTIVE QUARRY 



AND PARTS OF THE 



COASTAL PLAIN 



ABANDONED QUARRY 



O 10 av ' M, - t 20 30 



Plate II 



16 The Commercial Granites of North Carolina 

ern Piedmont ranks third; in production, however, it is second, due to the extensive quarrying operations 
at Mt. Airy, in Surry County. 

Dark colored diabase and schistose dikes of basic composition are most prevalent in the Piedmont 
Plateau and are mentioned in the descriptions of the individual areas. 

GRANITES OF THE NORTHEAST PIEDMONT 

The area included within the Northeast Piedmont begins at the fall line, or the line along which the 
Coastal-Plain sediments are in contact with rock types of the Piedmont Plateau, and extends westward 
across the granites, slates, and Triassic sediments to the contact with the main belt of volcanic slates, com- 
prising a part of the Central Piedmont. It also includes one granite area west of the Triassic-Slate con- 
tact in Orange County. The Virginia line constitutes the northern limit of the district, and an inland ex- 
tension of the Coastal-Plain sediments forms the boundary to the south through central Johnston and Har- 
nett Counties. (See Plate II.) 

The counties comprising the division which are partially underlain by granitic rocks include: Wake, 
Vance, Franklin, Warren, Granville, Northampton, Orange, Halifax, Johnston, and Chatham. Nash County 
and western Wilson County are also within the geographic confines of this area but have been discussed 
with the Coastal Plain because of the continuity of the underlying granite deposits with those present in 
Edgecombe County and central Wilson County in the Coastal Plain Province. The principal occurrences of 
granite in the Northeast Piedmont form finger-like bodies, extending southward across the area from the 
Virginia line. The largest of these bodies extends across Warren County, Franklin County, and eastern 
Wake County into the northwestern part of Johnston County and represents the southernmost extension of 
granite in the belt. Over most of the area, the rocks are covered by thick, buff to reddish-brown, granite 
residuum. The principal outcrop areas are of boulder or ledge-like form and are observed best along and 
adjacent to the major drainage and in deep highway and railroad cuts. The outcrops, though similar to 
those of the Coastal Plain, are in most instances larger in areal extent. The delineation of the granite de- 
posits, as shown on Plate II, is based largely on the color and other physical characteristics of the residual 
material in the area but is not nearly so difficult to determine as in the Coastal Plain because outcrops of 
fresh and sap granite are more numerous. The principal outcrop areas, hence the largest areas of present 
and past productivity, are located in Wake and Vance Counties. Present commercial production is restricted 
largely to the Rolesville area in Wake County and the Greystone area in Vance County, where large ton- 
nages of granite are crushed and marketed as concrete aggregate, road metal, and railroad ballast. Other 
quarries and small openings are found throughout the Northeast Piedmont but are abandoned at present. 

The importance of granite-gneiss in this area should be noted, since most of the past quarrying for build- 
ing stone was done in the vicinity of Raleigh, in an area underlain largely by gneisses of probably primary 
sedimentary origin. So far as could be determined, former granite-gneiss workings near Raleigh represent 
the largest quarrying of gneisses east of the Blue Ridge. One small quarry in the vicinity of Raleigh is en- 
gaged in the production of dimension stone to supply local demand. This operation utilizes a granite-gneiss, 
locally called "Wakestone." 

The commercial granite potential, including gneiss, in the Northeast Piedmont can be considered unlim- 
ited. The rocks are generally firm on outcrop and below the residual overburden, and the many abandoned 
openings formerly utilizing the granite in the production of dimension stone offer deposits which can be 
expanded readily in the production of crushed stone. Dikes and veins of varied composition are found in all 
parts of the Northeast Piedmont and where prevalent are discussed with the descriptions of individual areas. 

WAKE COUNTY 

Except for a narrow north-south trending band of Triassic sediments and volcanic slates along the west- 
ernmost boundary, Wake County is underlain by granitic rocks of two genetic types. Occupying the eastern 
and east-central part of the county are true plutonic rocks largely of granitic composition and medium- 
grained texture. Granite-gneiss and micaceous schist underlie the remainder of the county west of the 
granite belt, beginning along a line passing approximately 2 miles east of Raleigh. (See Plate II.) 



The Commercial Granites of North Carolina 17 

raleigh granite area 

Many years ago rather extensive quarrying operations were carried on in the immediate vicinity of 
Raleigh for the production of dimension and crushed stone for local use. The State Capitol building and 
many of the older churches and homes of the city are constructed of a granite-gneiss, locally called "Wake- 
stone." This type stone is a uniformly fine- to medium-grained rock of approximate granitic composition, 
usually displaying a marked parallelism of all mineral constituents. Colors range from light gray to grayish 
tan, which upon exposure weathers to a mottled tan. Large blocks of the stone almost inevitably show pene- 
tration by aplite or fine-grained pegmatitic material. Wakestone was formerly obtained from three large 
quarries, two of which were within the corporate limits of Raleigh. 

The City Quarries: Two large openings were worked in the vicinity of the National Cemetery, about 
1.5 miles east of the Capitol building, beginning about 1833 and continuing intermittently until after 1903. 
Stone from these quarries was used in the construction of the State Capitol buiding. According to Watson 
and Laney, jointing in the rocks of this area is at fairly close intervals and strikes approximately E. Within 
the quarries, many areas of mineral segregation are present and usually occur as vein-like bodies, conforming 
to an approximate N. strike. The vein and dike materials consist of pegmatite, aplite, and quartz, and all 
show evidence of minor displacement since intrusion. 

Petrographically, Watson and Laney describe Wakestone, as follows: 

". . . in order of their abundance . . . feldspar, quartz and biotite. The feldspathic constituent 
consists of the potash varieties, orthoclase and microcline, with a nearly equal proportion of striated 
acid plagioclase. Microcline nearly equals orthoclase in amount. . '. . micropoikilitic structure is 
fairly well developed. . . . Biotite is distributed through the sections. . . . Zircon and apatite ... 
complete the list of minerals." 

Based on the definitions given earlier in this report, Wakestone from these quarries falls into the class quartz- 
monzonite gneiss. 

The Sutton Quarry : A recent revival of interest in Wakestone for building purposes has resulted in the 
opening of a small quarry in north Raleigh, near Lassiter Mill. According to Mr. Sutton, the owner, dimen- 
sion stone of small size is used locally to a rather large extent, especially in the building or enlargement of 
schools and churches and as a trim stone. Stone from the small quarry is decidedly gneissic and corresponds 
in composition with the stone from the old City Quarries. Colors in the deposit are generally a gray-tan to 
mottled tan and present a pleasing appearance. The joint systems are well developed, but vein and dike 
materials are almost entirely absent. 

Other Quarries : Other openings in granite-gneiss were made in Wake County in the vicinity of the State 
Penitentiary and 2 miles northwest of Raleigh, both furnishing dimension stone for local use. In general, 
the rock type corresponds with that of the City Quarries, though locally it may become more or less gneissic. 

The Crabtree Quarry: This small bench-type quarry is located about 3.5 miles northwest of the Raleigh 
city limits, 0.75 of a mile south of U. S. Highway 70, and adjacent to Crabtree Creek. Although now aban- 
doned, the quarry has in recent years produced crushed stone for county road repairs and remains in excellent 
condition for further use. The rock is a light gray granite-gneiss of medium- to large-grained texture, in 
which dark silicates are almost entirely absent. Shear is prominent, cutting the deposit into blocks of small, 
irregular dimension. A thin section of the rock shows the following minerals and their percentages : 

Quartz 32% 

Orthoclase 35% 

Plagioclase 10% 

Biotite 8% 

Others (zircon, apatite, tourmaline, magnetite, 

calcite, muscovite, sericite) 15% 

Accordingly, the rock falls into the class granite-gneiss. Significant features observed in the thin section 
were: (1) numerous tangential grain contacts, which constitute the most prominent microscopic charac- 
teristic of the rock, (2) the presence of considerable sericite, formed by the alteration of the feldspar con- 
stituents, (3) the abundance of accessory minerals, and (4) fine mosaics of quartz filling the interstitial 



18 The Commercial Granites of North Carolina 

areas in the rock. Within the quarry, numerous small mineral veins, consisting of siderite(?), biotite, and 
muscovite, can be found occupying open joints and planes of shear, while other joint surfaces are coated 
with muscovite and radiated tourmaline crystals. 

ROLESVILLE GRANITE AREA 

Dimension Stone Quarry : The quarry is located about 50 feet east of the Rolesville School and within 
the southern limits of the community of Rolesville, in northeast Wake County. It is accessible by N. C. High- 
way 59. The deposit in which the bench-type quarry is developed outcrops in a gently dipping dome-like 
manner over approximately 1500 square feet. A considerable amount of dimension stone has been produced 
at this quarry, and though now abandoned it remains in an excellent condition for further operation. The 
rock is essentially massive, with only two directions of jointing noted over the entire area of outcrop. It is 
a light gray to pinkish-gray granite of uniform medium grain and is essentially unweathered throughout. 
In some places, the segregation of biotite interrupts the uniformity of texture, and many thin veins of binary 
granite cut the deposit along a northeast strike, which seemingly conforms to the strike of joints, N. 26° E. 
and E. Sheeting in the granite is well developed, permitting the quarrying of blocks of a uniform thicksnes 
of about five feet. Iron oxide stain is prevalent in some parts of the quarry. A thin section of the rock shows 
the following mineral percentages : 

Quartz 30% 

Orthoclase and microcline 34 % 

Plagioclase 28% 

Biotite 7 % 

Others (chlorite, sericite, apatite) 1% 

On the basis of this examination, the rock falls into the class quartz-monzonite. 

Lassiter Quarry : The Lassiter Quarry, located about one mile southeast of Rolesville, is the largest and 
among the most efficient crushed-stone operations in North Carolina. (Figure 1.) According to Mr. H. S. 
Satterwhite of the Bryan Rock and Sand Company, the quarry was first opened in 1922 and engaged exclus- 
ively in the production of street curbing until 1923, at which time crushing facilities were installed at the 
quarry. From 1924 to 1929, the principal products from the quarry were curbing, paving blocks, and crushed 
stone. During this period, curbing and paving blocks were shipped to points as distant as Philadelphia. 
Operation of the quarry was intermittent during the years 1929 to 1941, but it has since been operated on a 
full-time basis with the most modern equipment in all phases of the quarrying operation. The principal prod- 
ucts include concrete aggregate, road metal, and railroad ballast. Markets are supplied in North Carolina, 
Virginia, South Carolina, Georgia, and Florida. A large amount of stone from the quarry is marketed in 
Coastal-Plain cities of the State. At the present time, the quarry covers approximately half a square mile 
and averages more than 75 feet in depth. It is a pit-type opening, although the east end presents a reason- 
ably accessible entrance to the quarry. Overburden in the quarry area is negligible. 

The granite utilized by the quarrying operation at Rolesville varies from a light pinkish gray to a medium 
gray, even-granular, medium-textured rock, which in some places shows a slight coarsely foliated character, 
to a medium-grained, massive, white granite containing a small amount of biotite. Though variable in amount, 
the biotite is always evenly distributed. A thin-section analysis of the granite by the U. S. Bureau of Public 
Roads shows the following composition: 

Quartz 36% 

C1 r 



Orthoclase 51$ 



to 



Microcline 2% 

Biotite 11% 

According to the analysis, the granite of the Lassiter Quarry is a normal or biotite granite. 

WENDELL GRANITE AREA 

The principal occurrence of granitic rock in the Wendell area is about one mile east of the corporate limits 
of the town, in the eastern part of Wake County. A large quarry, Rockton Quarry, formerly operated by the 
Bryan Rock and Sand Company, has been developed in this vicinity in a rather pronounced dome-like body 



The Commercial Granites of North Carolina 



19 







20 The Commercial Granites of North Carolina 

of granitic rock covering about 100 acres. The quarry is about 500 feet square and was worked to an average 
depth of about 125 feet, beginning on a flat surface and expanding vertically and horizontally. Because of 
increased production at the company's Lassiter Quarry, this operation was abandoned about 5 years ago, 
and the quarry is now filled with water to a depth of about 50 feet. Prior to cessation of operation, the 
quarry furnished large amounts of crushed stone for use as concrete aggregate, road metal, and railroad 
ballast to Eastern North Carolina. 

The granite is light gray to pinkish gray and ranges in texture from even-granular, medium-grained 
rock to a distinctly porphyritic phase, in which half -inch to one-inch laths of plagioclase are the principal 
mineral constituent. Large segregations of biotite and quartz are commonly found in the medium-textured 
phase, which is richer in the two minerals than the highly feldspathic porphyritic parts of the deposit. The 
rock is moderately sheared, with the most prominent plane of jointing having a strike of N. 60° E. Most 
of the open fractures are coated with a thin veneer of biotite, and quartz and binary granite veins cutting 
the granite are common. Sheeting within the deposit is very irregular and because of shear, hardly detect- 
able. At some places, buff to reddish-brown residuum covering the granite attains a thickness of 30 feet. A 
microscopic examination of several thin sections, cut from the medium-grained phase of the granite and re- 
ported by the U. S. Bureau of Public Roads, shows the following minerals and their percentages in the rock : 

Quartz 32 % to 42 % 

Orthoclase 34% to 49% 

Plagioclase 0% to 21% 

Microcline 1% to 11% 

Perthite , 2% to 5% 

Biotite 0%to 8% 

Muscovite 0% to 3% 

The results of these analyses place the rock in the category of biotite granite, although one of the analyses 
shows a rock approaching quartz-monzonite. 

KNIGHTDALE GRANITE AREA 

The Knightdale granite area is located in southern Wake County, about 6.5 miles west of Wendell. The 
largest outcrops occur as low, flat-surface masses and large spheroidal boulders. The granite is very sim- 
ilar to that occurring in the Rolesville area, though the mineral composition appears more uniform. 

Abandoned Quarry: An abandoned quarry, covering approximately 1.5 acres, is located 1.5 miles east of 
the corporate limits of Knightdale and 0.1 of a mile north of the Norfolk Southern Railway. It is accessible 
by hard-surfaced road and a quarry road from Knightdale. According to local inhabitants, the quarry has 
produced dimension stone but more recently was a source of rock for crushing. It is reported to have been 
operated for about one month in 1950 in the production of crushed stone in small amounts. The quarry is 
now filled almost to the surface with water, and the depth of the quarry could not be determined. 

The granite is a uniformly light gray to pinkish-gray, even-granular rock of medium texture. Biotite is 
evenly distributed through the rock, and occasional quarter-inch laths of plagioclase, which nearly equals in 
amount the orthoclase constituent, can be seen in hand specimens of the granite. The rock body is cut by 
widely spaced vertical joints and rarely by veins of pinkish binary granite. The stone is well suited for use as 
small dimension stones and crushed material and is unweathered on the exposed surface. 

OTHER GRANITE AND GRANITE-GNEISS AREAS IN WAKE COUNTY 

Other areas of granite and granite-gneiss outcrops in Wake County can be found in the vicinity of the 
following communities : 

1. Zebulon: Granite of a type similar to that at the Rockton Quarry near Wendell occurs near Zebulon, 
and large flat-surface outcrops can be seen adjacent to U. S. Highway 264, southeast of Zebulon, in the east- 
ern part of Wake County. 

2. Wake Forest: Granite of a type similar to the Rolesville stone outcrops rather extensively in the 
vicinity of Wake Forest, in northern Wake County. 

3. Falls : Granite-gneiss, or Wakestone, crops out near the village of Falls, in north-central Wake County. 



The Commercial Granites of North Carolina 21 

VANCE COUNTY 

A large body of granitic rock underlies the central part of Vance County, being intrusive into the vol- 
canic slates in the western part of the county and gneisses and schists in the eastern portion of the county. 
(See Plate II.) The area of present commercial granite production in Vance County is located at Greystone; 
however, a considerable amount of dimension granite was produced some years ago about three miles north- 
east of Greystone, in the vicinity of Middleburg. 

GREYSTONE QUARRY 

The present Greystone Quarry, located along the Seaboard Air Line Railroad in east-central Vance 
County, is one of three openings made in the granite near the village of Greystone, the first of which was 
begun about 1885. In 1904, the quarry now in operation was about 100 feet square and had been worked 
to an average depth of less than 12 feet. This compares with an average depth of approximately 150 feet 
and an areal extent of 1,000 by 700 feet at the present time. This quarry has been in almost continuous 
operation since about 1900 and for many years furnished curbing, paving block, and crushed stone to cities 
as distant as Norfolk, Virginia. Crushed stone from the quarry is still marketed in Norfolk. Present pro- 
duction is limited to crushed aggregate, road metal, and railroad ballast. Ballast is shipped to points as 
distant as Florida, and other crushed products are marketed in Coastal-Plain cities in North Carolina as far 
east as Greenville. 

The granite, covered by 1 to 6 feet of buff colored residuum, is moderately gneissic, showing a rough 
parallel growth of the biotite constituent and is light pinkish gray in color. Segregations of biotite in the gran- 
ite are common, and a thin veneer of the same mineral occurs on many of the open- joint surfaces. Many gran- 
itic and fine-grained pegmatitic dikes and veins penetrate the rock and the principal joints, which strike N. 60° 
E. and N. 5° E. The rock is consistently medium grained, though occasional large grains of orthoclase tend 
to disturb the textural uniformity. A thin section prepared from a specimen of the rock shows the following 
mineral composition: 

Quartz 39% 

Orthoclase : 50% 

Plagioclase (oligoclase) 2% 

Biotite 6% 

Others (apatite, zircon, magnetite, muscovite, chlorite) 3% 

Accordingly, the rock falls into the class biotite granite. Of interest in the examination of this section was 
the extensive kaolinization of feldspars, the extensive chloritization of the biotite, and the considerable 
amount of muscovite and sericite, also derived from the alteration of the feldspar constituent. In addition, 
many quartz-feldspar intergrowths were observed. 

MIDDLEBURG QUARRY 

About three miles north of Greystone and one mile west of the village of Middleburg, in east-central 
Vance County, two large quarries were opened about 1900 and were operated on a small scale for many 
years, furnishing paving block and curbing to cities in Southeast Virginia. 

The granite from these quarries is remarkably similar in mineral composition to the granite at Grey- 
stone, though it is distinctly more gneissic and is darker in color as a result of an increase in the amount of 
biotite present. As in the Greystone granite, occasional outsized grains of orthoclase and segregations of 
biotite tend to disturb its medium texture. Only one plane of jointing, having a strike of N. 87° E., cuts 
the massive, flat-surface deposit, but binary granite dikes and quartz veins are found in all parts of the 
quarry area. The granite dikes range in thickness from a feather edge to one-half inch, but the quartz veins 
are rather uniformly about one inch in width. Residual overburden in the quarry area is negligible. 

The Middleburg granite is not well suited for any type dimension stone with the exception of rough 
curbing, and it is doubtful that the deposit at the old quarries could be utilized economically as crushed 
stone because of the massive character of the granite. 



22 The Commercial Granites of North Carolina 

Other Granite Areas in Vance County 

Other areas in Vance County in which granite outcrops are extensive are located along U. S. Highway 1, 
north of Henderson and in the vicinity of Williamsboro, located about 10 miles northwest of Henderson. Ac- 
cording to a microscopic examination by Watson and Laney, the granitic rock which crops out near Hender- 
son is a normal or biotite granite, showing a slight gneissic structure. 

FRANKLIN COUNTY 

Large boulder outcrops and flat-surface masses of granitic rock are rather numerous over the central and 
eastern portions of Franklin County and are especially notable in the vicinity of Louisburg, the county seat. 
To the west of Louisburg, along the county line, gneisses and schists similar to the rocks in western Wake 
County underlie a generally thick residual cover. A small part of northeast Franklin County is underlain by 
rocks of the Volcanic-Slate Series. (See Plate II.) The commercial utilization of granitic rocks has never 
been undertaken in Franklin County, though some areas appear to be worthy of commercial development. 

THE LOUISBURG AREA 

During the investigation, numerous outcrops of relatively fresh granite were observed in the vicinity of 
Louisburg, especially along the Tar River and N. C. Highway 56 between Louisburg and Franklinton. A thin 
section, cut from a specimen of the granite exposed along the Tar River in Louisburg, is described by Watson 
and Laney, as follows : 

"... a medium texture biotite granite, composed of . . . orthoclase, microcline, acid plagioclase, 
quartz, biotite, muscovite, apatite, zircon, iron oxide, chlorite and kaolin. Orthoclase is the predom- 
inant feldspar with but little microcline. . . ." 

According to this analysis, the rock is interpreted as representing a medium-grained biotite granite. A 
specimen of the granite collected by the author shows it to be a light gray massive granite of uniform med- 
ium texture, containing no parallelism of mineral constituents. The deposit, located near the center of Louis- 
burg, is cut into blocks of varying dimensions by joints, striking N. 75° W. and N. 20° W. Quartz veins occupy 
some of the joints and binary granite dikes up to 6 inches in width cut the deposit in many directions. A 
specimen of granite obtained from an outcrop along the State highway between Louisburg and Franklinton 
is very similar to the Louisburg granite. 

Dimension Stone Quarry : Approximately 12 miles west of Louisburg, near the county line, a small open- 
ing was made many years ago in a distinctly gneissic rock similar to the granite-gneiss in Wake County. The 
opening is about 75 feet in diameter and was worked to an average depth of about 12 feet. The small flat- 
surface outcrop in which the opening was made is cut by joints, striking N. 61° W. and N. 19° E., and many 
of the joints are filled with vein quartz. The stone is light gray to mottled tan in color and of a grain size 
intermediate between fine and medium. Its gneissic character is immediately apparent upon examination of 
hand specimens, and in appearance it is as desirable a stone for building purposes as the Wakestone of the 
Raleigh area of Wake County. Apparently, this quarry was worked many years ago for blocks of small 
dimensions for local building purposes. A thin section cut from a specimen of the granite-gneiss shows the 
following mineral composition : 

Quartz 38% 

Orthoclase 57% 

Biotite 4 % 

Others (apatite, chlorite, epidote, titanite) 1% 

The rock falls into the class herein defined as granite-gneiss. Of considerable interest in the examination of 
the thin section were the numerous tangential contacts between quartz grains and the overall "quartzitic" ap- 
pearance of the stone in the areas containing few or no dark silicates. The close proximity of the rock from 
this quarry to the schist-gneiss and granite contact, coupled with the microscopic properties, suggest a non- 
plutonic origin for the rock. 



The Commercial Granites of North Carolina 23 

basic dikes 

Massive diabase dikes of gabbroic composition are found in many places in Franklin County penetrating 
the granitic rock but seem especially prevalent along the highway between Louisburg and Franklinton. These 
intrusives are typical of the diabase dikes which occur in many parts of North Carolina from the granite 
areas of the Coastal Plain to the Blue Ridge. They are composed predominantly of plagioclase (labrado- 
rite), augite, olivine, with magnetite as the principal accessory mineral. The average strike of the dikes 
between Louisburg and Franklinton is roughly N. 40° W. 

WARREN COUNTY 

Granitic rocks are exposed in only a few places in Warren County, the principal areas being located 
around Warrenton, in the east-central portion of the county, and in the vicinity of Warren Plains, about 3 
miles to the north. Although approximately three-fourths of the county is underlain by granitic rock, resi- 
dual overburden attains great thickness over most of the county and accounts for the scarcity of outcrops. 
So far as could be determined, there has been no commercial granite production in Warren County. (See 
Plate II.) 

WARRENTON AREA 

The granite outcrops in the vicinity of Warrenton are uniformly medium grained, light gray in color, 
and in most of the exposures the rock is very slightly gneissic. Joints cutting the granite strike N. 30° W. 
and N. 50° to 60° E. A small quarry was opened in the granite in the west corporate limits of Warrenton 
many years ago to furnish crushed material for improving the streets of the town but has been abandoned. 
A thin section prepared from a specimen of this granite is described by Watson and Laney : 

"... a thin section of the rock reveals a . . . biotite-hornblende gneiss. . . . Besides biotite and 
hornblende, the principal minerals in the rock are orthoclase, with an equal or greater amount of 
striated plagioclase, quartz, epidote, and chlorite. Microcline entirely fails. The hornblende nearly 
equals biotite in amount. . . . Quartz is equal to or greater in amount than the feldspathic constitu- 
ent." 

According to this analysis, the rock should be placed in the class quartz-monzonite. 

WARREN PLAINS AREA 

Granite similar in composition to that found in the Warrenton area outcrops about 3 miles north of War- 
ren Plains and, like the granite at Warrenton, has never been utilized commercially. In some phases of the 
rock, almandite(?) garnet becomes a prominent accessory mineral. 

Warren County State Quarry: In recent years the State Highway and Public Works Commission has 
developed a quarry in a light gray, fine- to medium-grained granite in southwestern Warren County, 6.5 miles 
southwest of Warrenton, in the vicinity of the village of Afton. This granite deposit outcrops as a prominent 
dome-like body, standing about 75 feet above an adjacent creek. It is intricately jointed and intruded by vein 
quartz. The joints strike N. 69° E., N. 44° W., and N. 17° W. Sheeting in the granite is poorly developed. 
The presently abandoned quarry is typical of the small bench-type quarry developed in many places across 
the State by the State Highway and Public Works Commission. It covers about one-half acre. 

The granite is an even-granular massive rock, showing a uniform distribution of biotite through most 
of the deposit ; however, large prominent segregations of the biotite up to 6 inches across are found in some 
places within the quarry. Many of the biotite segregations are crumpled and mashed to such an extent as to 
render them gneissic. A thin section of the stone from the quarry shows the following mineral composition : 

Quartz " 32 % 

Orthoclase . 47% 

Plagioclase 13% 

Biotite 7% 

Others (muscovite-sericite, zircon, magnetite) 1% 

The rock is a biotite granite. Interlocking quartz and feldspar grains and peripheral shattering of the quartz 
constitute the most pronounced microscopic characteristics of the rock. 



24 The Commercial Granites of North Carolina 

Old Quarry : An abandoned quarry near the village of Oline, about 6.75 miles northeast of Warrenton, 
was visited briefly during the Warren County investigation. The granite from this quarry is very similar 
in appearance to the rock utilized at the State quarry near Afton, though it shows a very slight coarse folia- 
tion. As in the Afton deposit, this rock is highly jointed and intruded by vein quartz. 

GRANVILLE COUNTY 

The occurrence of granitic rocks in Granville County is limited to the east-central portion of the county., 
beginning at the Virginia state line on the north and terminating in the south-central section of the county 
upon contact with sedimentary rocks of Triassic age. The remainder of the county is underlain by rocks of 
the Volcanic Slate Series and Triassic sediments. (See Plate II.) Boulder or flat-surface bodies of light 
gray, even-granular, massive granite were observed in a few localities in Granville County, being especially 
prominent in the vicinity of Oxford, the county seat, and along U. S. Highway 158 east of Oxford. So far 
as could be determined, none of the granite deposits in these areas has been utilized commercially and in only 
one locality, near Wilton in the southeastern section of the county, is granite presently utilized by the State 
Highway and Public Works Commission. 

State Quarry : A small bench-type quarry, operated by the State Highway and Public Works Commission 
for the production of crushed stone for local road improvement work, is located 1.75 miles east of Wilton, 
in the extreme southeastern part of Granville County. The granite deposit in which the quarry is developed 
crops out as boulders and flat-surface masses over an area of approximately one-fourth square mile. The 
granite is a massive, deep pink, even-granular rock of medium texture. The prominent mineral constituents 
are quartz, pink feldspar, and uniformly distributed biotite. The exposed granite is cut into irregular blocks 
of varying dimensions by rather closely spaced joints, having strikes of N. 34° E. and N. 3° W., and further 
by horizontal sheeting planes at intervals of 1 to 4 feet. At many places in the quarry, vein quartz fills open 
joints ; while in other places the joints are either unfilled or their open surfaces are coated with an iron sul- 
phide mineral. At the time of the field work, the quarry was roughly circular and covered an area having a 
diameter of approximately 250 feet. A thin section prepared from a specimen of the granite from this 
quarry showed the following mineral composition : 

Quartz J 29 % 

Orthoclase 38% 

Plagioclase ( oligoclase ) 29 % 

Biotite 3 % 

Others (muscovite, chlorite, apatite, and magnetite) 2% 

According to this analysis, the rock falls into the class herein defined as quartz-monzonite. The most promi- 
nent microscopic characteristics of the rock are the closely interlocked feldspar and quartz grains, myrme- 
kite, intergrowths of quartz and orthoclase, and the pronounced alteration of the feldspar constituents. 

NORTHAMPTON COUNTY 

The greater part of Northampton County lies in the Coastal Plain Province, granitic rocks cropping out 
only in the extreme northwestern part, in the vicinity of Camps Store and Henrico. (See Plate II.) 

THE HENRICO AREA 

A small, flat-surface mass of granite-gneiss crops out one mile west of the village of Henrico, in the 
northwestern part of Northampton County, about 11.5 miles WNW. of Camps Store. This small exposure of 
gneissic granite covers about 2 acres and is entirely free from vertical joints. The rock is a dark pinkish- 
gray, medium-grained, distinctly gneissic granite, showing complex intrusion by quartz, binary granite, 
and normal granite of a medium-grained, massive character. The granitic intrusives are lighter gray than 
the older gneiss and combine with the gneiss to form variegated migmatitic patterns through the entire 
deposit. The injection of the later materials has taken place along a consistent north strike. In many of 
the granite penetration zones, fragments of the older rock occur as essentially unaltered inclusions, and the 
segregation of biotite is common in the same areas. A distinct and regular sheeting of a convex-concave pat- 



The Commercial Granites of North Carolina 25 

tern divides the rock into sheets approximately 4 feet in thickness. A thin-section analysis of the gneissic 
granite shows the following mineral composition : 

Quartz 38% 

Orthoclase 53% 



Biotite-hornblende 7% 

Others (microcline, chlorite, magnetite, apatite, 

zircon, and plagioclase) 2% 

The rock has the mineral composition of biotite granite. 

ORANGE COUNTY 

Orange County lies almost entirely within the main belt of the Volcanic-Slate Series ; however, granitic 
rocks are exposed in the southwestern portion of the county and schists and gneisses, in the extreme north- 
western sections of the county. (See Plate II.) 

The granitic rocks of Orange County are interesting because of the great variation in character between 
the granite of the southern part of the county and the granite exposed in the east-central portion of the 
county, near Hillsboro. In general, the granite exposures along the county line to the south of Chapel Hill 
are light grayish pink to deep pink and are more often even-granular, medium-textured granite of uniform 
composition. Feldspar is the predominant mineral in this granite, with quartz and other minerals usually 
constituting less than 25 percent of the total volume. In the vicinity of Chapel Hill, the granite assumes a 
rather uniform light gray color, in general contains a wider variation of mineral constituents, and contains 
in many places a considerable amount of epidote and inclusions of older rock. To the north of Chapel Hill, 
in the vicinity of Hillsboro, the granite contains numerous irregular inclusions of older basic volcanic rocks, 
which, in places, seem to have altered extensively the original granitic material by enrichment of the magma 
during assimilation. The Bacon Quarry, presently operated by the State Highway and Public Works Com- 
mission, is the only stone operation in Orange County utilizing granitic rocks. 

THE BACON QUARRY 

The Bacon Quarry of the State Highway and Public Works Commission is located in east-central Orange 
County, 4.3 miles northeast of Hillsboro and is engaged in the production of crushed stone for local road and 
highway improvement. The deposit in which the small bench quarry is developed forms a roughly circular 
hill, standing about 100 feet above the surrounding terrain. The rock is medium to dark gray, containing 
gray to pinkish-gray feldspars and quartz and numerous inclusions of the older volcanic rocks into which 
it was intruded. The texture is not uniform, and the mineral composition apparently varies from place to 
place within the quarry. The rock is distinctly a massive hybrid material, formed during the intrusion in 
volcanic slates of a magma which possessed poor assimilatory capacity. Inclusions in the rock range from 
less than one-half inch to more than 2 feet across and show various stages of reaction peripheral to their 
borders. Considerable epidote is disseminated through the rock, and veins and smears, or coatings, of epidote 
appear on the open-joint surfaces. Veins of calcite, up to 6 inches across, occur as joint filling in the highly 
sheared deposit. A thin section cut from a hand specimen of the rock shows the following mineral composi- 
tion: 

Quartz 13% 

Orthoclase 13% 

Plagioclase 62% 

Epidote 10 % 

Others (sericite, magnetite) 2% 

According to this analysis, the rock should be placed in the category quartz-diorite(?). Of interest in the 
examination of the thin section were the innumerable fine inclusions of epidote, giving the rock an extremely 
"dusty" appearance under the low-power lens. A considerable number of idiomorphic feldspars and the 
scarcity of interlocking mineral grains are also prominent microscopic features of the rock. 



26 The Commercial Granites of North Carolina 

OTHER COUNTIES 

Halifax, Johnston, and Chatham Counties constitute a part of the Northeast Piedmont and are partially 
underlain by granite rocks similar to those in adjacent counties. Because of a thick residual cover and con- 
sequent scarcity of outcrops, little time was spent in these counties during the investigation. 

A porphyritic granite, probably a granodiorite, was seen along N. C. Highway 48 near Brinkleyville in 
the western part of Halifax County, during the investigation and was found to be highly weathered and 
friable. The granite contains large laths of plagioclase up to 1.5 inches across and often biotite and quartz 
grains of a uniform size of about one-half inch. Most of the feldspar grains show moderate to strong kaolin- 
ization. The rock is exposed for about 1.5 miles along -the highway. 

In Johnston County, granitic rock outcrops prominently in the vicinity of Clayton. Because of the time 
limitation during the investigation, the rock was not examined closely. 

A southern extension of the granite body in Orange County crops out in northern Chatham County, 
about 2 miles south of the county line along U. S. Highway 15-501. The granite, similar to the deep pink 
variety found in southern Orange County, is even-granular, medium textured, and of a uniform composition. 
Feldspar is the predominant mineral component, with quartz and dark silicates usually occurring in small 
quantities of not more than 20 to 25 percent. In the vicinity of Bynum, 3 miles northeast of Pittsboro, light 
gray, medium-textured granite penetrates volcanic rocks of the Volcanic-Slate Series. 

GRANITES OF THE CENTRAL PIEDMONT 

The Central Piedmont is underlain largely by the most extensive bodies of igneous rocks in North Caro- 
lina, the Main Igneous Belt, or Carolina Igneous Belt of Watson and Laney, and the main body of slaty vol- 
canic rocks, forming a large part of the Volcanic-Slate Series in the State. The eastern boundary of the 
Central Piedmont is formed by sedimentary rocks of Triassic age, and the eastern boundary of Person 
County, while the western limit is formed by the extensive pre-Cambrian gneiss-schist complex and the 
western line of Rockingham County. Virginia and South Carolina limit the region on the north and south, 
respectively. (See Plate III.) 

The Main Igneous Belt is formed by a continuous body of granitoid rocks lying along a northeast-south- 
west axis from the South Carolina line to western Person County, attaining the greatest width, 35 miles, 
in the central and southern parts of the belt and the least width, 10 miles, at its northern terminus in Person 
County. It is within this belt that the widest variety of granitoid rocks in the State occurs. Of the various 
types present, perhaps granite and quartz-monzonite are the most aboundant ; however, large areas within 
the divisions contain granodiorite, diorite, gabbro, and augite-syenite, all of which have been utilized more 
or less in the production of commercial stone. Also within this belt of rocks are large areas of older gneisses 
and schists, which interrupt locally the continuity of the granitoid rock bodies. Throughout most of the 
Central Piedmont, thick, buff to reddish-brown granite residuum covers fresh rocks ; however, outcrops are 
more frequent and much larger than in the Northeast Piedmont, where boulder outcrops are common in 
many areas. 

The geological associations between acid and basic rocks in the Central Piedmont become very complex 
in some localities, especially in areas adjacent to the Volcanic-Slate Series, but the complexities are not lim- 
ited to this zone. Even in the central areas of the Main Igneous Belt, granite-diorite complexities are fre- 
quent and of such a nature as to pose very complicated associations. In many places, the relationship of 
granites and basic rocks strongly suggests multiple intrusion with granite penetrating older diorite-gabbro, 
while in other localities the relationship suggests diorite-gabbro invasion of granite. Dike materials of 
varied composition are prevalent throughout the region and are mentioned briefly in the appropriate section. 
The presence of gneissic structure in some of the granitic rocks of the Central Piedmont is sufficiently pro- 
nounced to suggest some dynamic metamorphism prior to or after consolidation of the emplaced magma. 
In others, the parallelism is almost certainly the result of incomplete assimilation, or a partial replacement 
by granite of the older gneissic and schistose rocks. 

That portion of the Central Piedmont underlain by granites and related rocks includes parts of 15 coun- 
ties, which, in order of granite and granite-gneiss production and commercial granite potential, are Rowan, 



The Commercial Granites of North Carolina 



27 



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28 The Commercial Granites of North Carolina 

Guilford, Forsyth, Caswell, Davidson, Iredell, Cabarrus, Rockingham, Gaston, Mecklenburg, Davie, Ala- 
mance, Lincoln, Catawba, and Person. At present, commercial granite production is limited to Rowan, 
Guilford, and Forsyth Counties, and granite-gneiss is utilized in the production of crushed stone in Caswell 
County. 

Most of the largest and best known granite areas in the State are included in the Central Piedmont, the 
most important of which is the Salisbury area of Rowan County, where the production of both dimension 
and crushed stone constitutes important industries. Other important granite-producing areas include 
Stokesdale, High Point, Jamestown, McLeansville, and Greensboro, in Guilford County, and Winston-Salem, 
in Forsyth County, all of which are engaged exclusively in the production of crushed stone. 

ROWAN COUNTY 

Rowan County is underlain by plutonic rocks of varied physical and chemical characteristics and rocks 
of the Volcanic-Slate Series. The volcanic rocks, flows and pyroclastics, occupy the southeastern quarter 
of the county, and granitic rocks are found in the remainder of the county. 

Because of the unusual availability and superior quality of the granitic rocks, the quarries in the 
county are among the principal and most important sources of commercial granite in North Carolina. Di- 
mension granite is quarried in the vicinity of Granite Quarry, about 5 miles southeast of Salisbury, largely 
along and adjacent to a prominent ridge of un weathered granite. The ridge begins about 4 miles east of 
Salisbury and is more or less topographically prominent northeastward for 12 to 14 miles. The granite 
composing the ridge ranges from various shades of pink to standard light gray, even-granular granite, and 
all colors are utilized commercially at present, the pink varieties from the quarries being famous in all 
parts of the United States. The principal crushed-stone area in Rowan County is near Woodleaf, 9 miles 
northwest of Salisbury, where a large quarry is developed in rocks of the granite-diorite-gabbro complex. 

Rowan County contains many operating and abandoned quarries and small openings, the more impor- 
tant of which are mentioned or described in the following order: (1) The Harris Granite Quarries, (2) The 
Quarries of the Salisbury Granite Industries, Inc., (3) The J. A. Logan Granite Company's Quarry, (4) 
Other Dimension Stone Quarries, (5) The Woodleaf Quarry, and (6) Other Granite Areas. 

THE HARRIS GRANITE QUARRIES 

The Harris Granite Quarries Company is among the oldest producers of crushed and dimension granite 
in Rowan County and is presently engaged in the quarrying and finishing of Balfour Pink Granite, Carolina 
Pink Granite, and Salisbury Gray Granite. In addition to the large output of dimension stone, a crusher 
is installed at the Balfour Quarry for utilizing the rubble from the dimension-stone operations. According 
to Mr. A. L. Harris, mining engineer, the annual production of dimension stone from the company's two 
active quarries averages approximately 20,000 cubic feet, most of which is the Balfour Pink and the Caro- 
lina Pink varieties. Dimension-stone production at the quarries is divided into two classes: monumental, 
which constitutes 80 percent of the total ; and building, which accounts for the remainder. Building-stone 
production is restricted largely to blocks of small dimensions for local use and paving blocks for use as tube 
liners in industrial grinding equipment. Recently large blocks of granite have been marketed for use as 
base mounts for precision instruments, the Balfour Pink granite being especially well adapted for this pur- 
pose because of an extremely low coefficient of expansion. The capacity of the stone crusher at the Balfour 
Quarry is reported to be about 6,000 tons per month ; however, the lack of sufficient rubble sometimes forces 
the cessation of crushing operations for short periods. 

The two active quarries of the company producing rough stone employ modern equipment, including 
steel derricks, air drills, and quarry bars (channel bars). Rough-cut granite from the quarries is finished 
in a well-equipped plant in Salisbury and shipped by rail and truck to large markets in the northeastern and 
west-central parts of the United States and smaller markets locally and in the Southeast. 

The principal quarries of the Harris Granite Quarries Company are: (1) The Balfour Quarry, (2) The 
Carolina Quarry, (3) the Dunns Mountain Quarry, (4) The American Quarry, (5) The Shuping Quarry, 
and (6) The Old Rowan Granite Company's Quarry. 



The Commercial Granites of North Carolina 



29 



The Balfour Quarry : This quarry is located one-half mile southeast of Granite Quarry, in south-central 
Rowan County, 0.3 of a mile west of U. S. Highway 52. The deposit in which the Balfour Quarry is developed 
constitutes a moderate topographic rise and is a part of the granite ridge of the southeastern part of Rowan 
County. The present quarry, a pit-type opening, ranges from 100 to more than 150 feet in depth and is approx- 
imately 300 by 800 feet in horizontal dimension. Over most of the quarry area, 1 to 12 feet of yellowish-brown 
residual decay and partially decayed granite have been removed during the quarrying operations. The de- 
posit is essentially massive, being cut by widely spaced joints which strike N. 10° E. and N. 70° W. Of con- 
siderable interest during the inspection of the quarry was the relationship of the principal plane of jointing, 
N. 70° W. and the color of the granite. At the north end of the quarry, the deposit consists of medium gray, 
even-granular, medium-grained granite, which continues toward the south end of the quarry to a point at 
which the principal joint surface cuts the deposit. At this point, in a space of only 2 to 3 feet, the color passes 
transitionally to a bright pink granite. The pink color continues for about 30 to 40 feet and changes to a dis- 
tinctly lighter pink granite immediately beyond a joint surface, parallel to the first. Toward the south end of 
the quarry, the light pink granite grades slowly into a bluish-gray granite and further on, to a blue-gray-pink 
hybrid rock. Natural sheeting planes, if present in the granite, are not distinguishable from the many arti- 
ficially induced planes. The greatest production from the quarry consists of a bright pink, slightly gneissic 
granite, in which dark silicate minerals are almost entirely absent. A thin section cut from the Balfour 
Pink granite shows the following mineral composition : 

Quartz 32% 

Orthoclase 35% 

Plagioclase 33 % 

Others (muscovite-sericite, apatite, titanite, 

magnetite, and chlorite) 2% 

According to this analysis, the rock is a quartz-monzonite. The most prominent microscopic feature of the 
rock is the pronounced interlocking character of feldspar and quartz grains. 

The Balfour Quarry has been in almost continuous production for more than 40 years, and it is estimated 
that 20,000,000 cubic feet or more of granite have been removed during its operation. Much of this pro- 
duction has been shipped to all parts of the United States and other parts of the world, and during the past 
40 years pink granite from the Balfour Quarry has become a standard on the granite market of the United 
States. The principal products from the quarry are monumental stock, paving blocks, large building blocks, 
small building blocks, and curbing. Figure 2 shows paving blocks of pink granite stacked and ready for 
shipment from the Balfour Quarry. The stone is quarried by using plugs and feathers and channel bars to 
separate the blocks from the quarry wall and is removed from the quarry by electrically operated hoists. 
Subdivision of the large blocks is accomplished by plug and feather wedging. The granite is reported to work 
well, and it takes a brilliant abrasive polish. 




Figure 2. Paving Blocks, Balfour Quarry, Rowan County 



30 The Commercial Granites of North Carolina 

The Carolina Quarry: The Carolina Quarry is located 4 miles southeast of Salisbury, immediately north- 
east of Dunns Mountain. The granite is a medium pink, even-granular, medium-grained stone, comparable 
in physical characteristics and color to the Balfour Pink ; and, like the Balfour stone, it works well and takes 
an excellent abrasive polish. The granite is essentially the same rock as that quarried at the nearby Salis- 
bury Granite Industries, a thin-section analysis of which can be found on page 31. It is a shallow, pit-type 
quany, roughly rectangular in plan and covering about 3 acres. Work at the quarry is intermittent, and 
water had partially filled the opening at the time of the investigation. Prominent but widely spaced joints 
cut the deposit at N. 45° E. and N. 25° W., but sheeting planes appear entirely absent below a 1- to 2-foot 
surface sheet of partially decayed granite. Residual overburden attains thicknesses up to 5 feet in the 
vicinity of the quarry. The granite from the Carolina Quarry is used principally for monuments. 

The Dunns Mountain Quarries : Dunns Mountain, the most prominent topographic feature in the Rowan 
County granite area, was the scene of considerable quarrying activity in past years; however, the extreme 
toughness and the poor workability of the stone, due to the lack of well-developed rift and grain, have resulted 
in the complete closing of the quarries. The "mountain" is located 4 miles southeast of Salisbury and 1.5 
miles east of U. S. Highway 52, in the east-central part of Rowan County. Several quarries operated on the 
slopes of Dunns Mountain produced both gray and pink varieties of granite for many years, production be- 
ing restricted largely to blocks of varying dimensions and curbstone. Both the pink and gray granite of the 
Dunns Mountain deposit are even-granular and alike in mineral composition, differing only in the color of 
the orthoclase feldspar constituent. Joints, having strikes of about N. 70° E. and N. 55° E., traverse the 
deposit at wide intervals, and in some places the joint surfaces are coated with a thin veneer of epidote show- 
ing slickenside striations. Residual overburden is very thin or absent, and steep slopes developed in granite 
can be seen at almost any place on the mountain. A thin-section description of the pink granite by Watson 
and Laney shows the following mineral constituents: 

". . . an aggregate of feldspar and quartz with no dark bisilicate. . . . Finely striated acid plagio- 
clase may equal or exceed . . . the potash feldspar. Microcline is present only in subordinate 
amounts. . . . scattered grains of magnetite . . . are noted through the section." 

On the basis of this description, the granite falls into the class quartz-monzonite, though the apparently 
excessive amount of plagioclase in some phases of the rock may place it in the class granodiorite. 

The American Quarry: Beginning immediately southwest of Dunns Mountain and continuing to within 
one-half mile of Granite Quarry, a series of small openings and prospects have been made in gray, medium- 
textured granite on a tract of land formerly known as the McCanless property. This series of small open- 
ings is terminated at the southwest end by the American Quarry, a large, water-filled, abandoned opening. 
The quarry is approximately 200 by 500 feet in areal dimension and more than 100 feet deep. The granite 
is a light gray, medium-textured rock and is reported to work well and take a brilliant abrasive polish. Joints, 
having strikes of N. 35° W. and N. 15° E., cut the granite at moderately wide intervals, and most of the joint 
planes are slickensided. Overburden in the quarry area ranges from 5 to 10 feet and is underlain by 1 to 10 
feet of sap granite. During operation, both dimension and crushed stone were produced in large quantities, 
dimension stone having been shipped to points as distant as Reading, Pennsylvania, and Washington, D. C, 
as early as 1903. 

The Shuping Quarry: The Shuping Quarry is located in the town of Faith, 5 miles south of Salisbury 
and 2 miles west of U. S. Highway 52. Owned by the Harris Granite Quarries Company, the Shuping Quarry 
is leased to J. T. Ritchie for the production of dimension granite. 

The quarry is developed in a low dome-like mass of light gray to very slightly pinkish-gray, medium- 
grained granite, which crops out over approximately 3 acres. The granite is essentially fresh from the sur- 
face downward. Vertical joints, at widely spaced intervals, cut the deposit in the following directions: N. 
10° E., N. 10° W., N. 45° E., and N. 50° W., and sheeting planes divide the granite into layers, ranging in 
thickness from 6 inches at the surface to about 10 feet in the lower parts of the shallow, bench-type quarry. 
The granite is an aggregate of closely interlocked grains of quartz and feldspar, about 10 percent of uniform- 
ly distributed biotite, and a small amount of epidote. Well developed rift and grain in the deposit respond 
excellently to quarrying and subdivision by plug and feather wedging. The principal products from the 
quarry are building blocks of small dimensions for local use and curbing and sills for shipment out of the State. 



The Commercial Granites of North Carolina 31 

The Jones Quarry, located two-tenths of a mile southeast of the Shuping Quarry, is also operated by 
Mr. Ritchie for the production of small building blocks, the granite being similar to that from the Shuping 
Quarry but of a lighter color because of less biotite. 

The Old Rowan Granite Company's Quarries: Within the corporate limits of Granite Quarry, consider- 
able quarrying activity was carried on at several openings from about 1900 to as late as 1930. Two large 
quarries are located about 100 yards northeast of the railroad depot, and smaller openings are found at close 
intervals to the southwest and toward the Balfour Quarry, to the southeast. Granite from these quarries 
is similar in composition and texture. A hand specimen of the light gray granite shows closely interlocked 
grains of quartz and feldspar, no biotite, and a considerable amount of the accessory mineral, magnetite. 
Even in a hand specimen, kaolinization of the feldspar constituent is apparent. 

The deposit forms a large dome-like mass, covering about 4 acres, and the larger of the two bench-type 
quarries developed in the deposit covers about an acre. The depth could not be determined because of water 
in the quarry, but it is reported to be in excess of 30 feet. Joints, striking N. 40° E. and N. 40° W., cut the 
deposit into blocks of varying dimensions. Residual decay and sap granite covering the granite range from 
5 to 15 feet in thickness. 

QUARRIES OF THE SALISBURY GRANITE INDUSTRIES, INC. 

Since its entrance into the Salisbury granite area in 1932, the Salisbury Granite Industries, Inc., has 
become one of the most efficient and modern granite quarrying operations in the Nation, The granite area 
presently controlled by this company lies approximately 1 mile northeast of Dunns Mountain and 4 miles 
southeast of Salisbury. The deposit is characterized by extensive flat-surface and boulder outcrops of med- 
ium-grained, even-granular, pink granite of extreme hardness but excellent workability. A total of eight 
openings has been made over the area, but present quarry operations are confined largely to a single opening 
developed in massive, pink granite in the southeastern part of the property. Production from the quarry is 
limited to dimension stone of varying sizes for finishing into monumental stock of the finest quality. The 
principal opening, a pit-type quarry rectangular in shape, is about 150 feet in length and 120 feet in width 
and has been worked to an average depth of 35 feet in about 4 years of operation. Production from this 
quarry apparently has exceeded 500,000 cubic feet, the larger part of which has been available for finishing 
and marketing. Shipments from the plant are made by motor freight and railroad to markets throughout the 
United States. Recently, a shipment was made to Hawaii. The stone is marketed under the trade name 
"Salisbury Pink Granite," and the annual production averages 50,000 to 75,000 cubic feet. 

The deposit in which the principal quarry has been developed is cut by very widely spaced and largely 
closed joints, having strikes of N. 50° E. and N. 25° W. These joints in no way interfere with the production 
of dimension stone of any desired size. Plug and feather wedging and channel bar separation are employed 
ing the quarrying of the granite as well as in the subdivision of the large blocks. Electrically operated steel 
derricks and hoists are used to remove the blocks from the quarry. Because natural sheeting planes are 
absent in the deposit, it is necessary to rely on artificially induced sheets for the horizontal parting of the 
granite. Black powder is used for cleaving sheets of any desired thickness, and usually a single lift is made 
over an area of 1,000 to 2,000 square feet and worked until exhausted. Because of efficiency of operation, 
waste from the quarrying procedure is held to a minimum. The granite is cut and finished in a modern, 
well-equipped plant into various types and sizes of monuments and to a lesser extent finished building blocks. 
The plant is equipped with gang saws, contour machines, high-speed polishing mills, and diamond saws. Ac- 
cording to Mr. C. R. Deadwyler, manager of the quarries and finishing plant, wire saws will soon be installed 
to add facility to the plant's operation. 

The granite is a bright pink rock, showing an even distribution of the quartz and feldspar constituents 
and minor amounts of bright green epidote and bluish magnetite. A thin section cut from a hand specimen 
of the granite shows these minerals in the following percentages : 

Quartz 33% 

Orthoclase 47 % 

Plagioclase 19% 

Others (biotite, epidote, magnetite, and muscovite)_ 1% 



32 



The Commercial Granites of North Carolina 




The Commercial Granites of North Carolina 33 

According to this analysis, the rock is placed into the class granite ; however, the normal amount of bisilicate 
minerals in granite is not present in this stone. The most pronounced microscopic characteristic of the rock 
is the closely interlocked grains of quartz and feldspar and the shattered appearance of the grains. 

During the course of the investigation, quarrying operations were observed both in the crushed-stone 
and dimension-stone industries, but none has been more efficiently developed than the principal quarry of 
this company. 

THE J. A. LOGAN GRANITE COMPANY'S QUARRY 

The J. A. Logan Quarry is located in the southern corporate limits of the town of Faith, 5.5 miles south- 
west of Salisbury. The area in which this small pit-type quarry has been developed is characterized by low, 
flat-surface outcrops of granite and a few widely scattered granite boulders. The quarry is roughly circu- 
lar, with a diameter of about 150 feet and an average depth of approximately 20 feet. The deposit is essen- 
tially massive, containing neither well defined planes of jointing nor sheeting planes of any consequence, 
rendering it necessary to use the plug and feather wedge method and the channel bar for the separation of 
blocks from the quarry wall. Lift sheets are produced over areas up to 2,000 square feet, using the black 
powder method; however, due to the horizontal attitude of the rift, a lifted sheet can be subdivided hori- 
zontally to any desired thickness by the use of plugs and feathers. The operation is modern in every way, 
the equipment consisting of electrically operated steel derricks and hoists, air drills, and channel bars. The 
principal products from the quarry are monumental stone, building stone of large dimensions, and small build- 
ing stones for local use. According to Mr. J. A. Hosselton, quarry superintendent, annual production ex- 
ceeds 35,000 cubic feet, most of which is shipped by rail to cutting and finishing plants in Northeastern 
United States and also to the cutting and finishing plant at Mt. Airy, Surry County. 

The granite, a medium-grained, even-granular rock, ranges in color from a faint pinkish-white, market- 
ed under the trade name Arabian Pink, to a light pink variety, marketed as Coral Pink. The pinkish color 
of the Arabian Pink variety from the quarry is due to minor oxidation (?) of the iron oxide mineral mag- 
netite, while the Coral Pink stone owes the pink coloration to an even distribution of light pink feldspars in 
the rock. The mineral constituents are distributed uniformly through the granite and possess a strong in- 
terlocking character. A thin section cut from a specimen of the Arabian Pink stone shows the following 
mineral percentages : 

Quartz 25% 

Orthoclase 32% 

Plagioclase 42% 

Others (magnetite, epidote, titanite, biotite) 1% 

According to this analysis, the Arabian Pink granite is a quartz-monzonite. 

OTHER DIMENSION STONE QUARRIES 

Many abandoned or sporadically operated granite quarries and small openings are found in many areas 
in and around the towns of Faith, Granite Quarry, Rockwell, and Barbers Junction, in Rowan County. In 
the area around Granite Quarry, more than 25 such openings were observed within a two-mile radius, and a 
similar number of small openings probably exists in the area around Faith. 

Two quarries not previously discussed merit at least a short description because of the products from 
one and the rock type formerly utilized at the other : 

The Barnhardt Quarry: This quarry is located in the town of Faith, a few hundred feet southwest of 
the J. A. Logan Company's quarry, and is developed in a rock type similar to the Arabian Pink of the Logan 
Quarry, though the minor iron oxide stains are absent, rendering the stone a pleasant light gray to white. 
At places in the quarry, the granite grades to a light pink. It is a pit-type opening and is partially filled 
with water. According to Mr. McCombs of Faith, the granite works very well into curbing and paving 
blocks. The principal products from this intermittently operated quarry are curbing, tube mill liners, and 
grinding pebbles, the mill liners and pebbles being for use in industrial grinding machines in which the fin- 
ished product must be extremely low in iron content. 



34 The Commercial Granites of North Carolina 

Thefeear Poplar Gabbro Quarry: The Bear Poplar Gabbro Quarry (McGalliard Quarry) is the name giv- 
en the abandoned quarry of the old Consolidated Granite Company near Bear Poplar, 12.5 miles west of Salis- 
bury and 5.5 miles southwest of Barbers Junction. The quarry is developed in large boulders and flat-sur- 
face outcrops of black, medium-grained, even-granular gabbro (norite) and is reported to have been worked 
for dimension stone as early as 1899. In 1903, Watson and Laney reported the stone was marketed as black 
granite in Ohio, New York, Indiana, and several southeastern states and was becoming a popular monu- 
mental stone in some parts of North Carolina. The deposit appears to be a large differentiated body of 
gabbro, though it is somewhat similar in composition and texture to the ophitic textured, or biabasic, dikes 
found throughout the Piedmont Plateau in North Carolina. A thin-section description of this stone by Wat- 
son and Laney follows : 

". . . containing much biotite, . . . orthorhombic and monoclinic pyroxenes largely hypersthene, 
plagioclase, a little orthoclase, some hornblende, a sprinking of quartz, and titaniferous magnetite." 

THE WOODLEAF QUARRY 

The Woodleaf Quarry is located in the village of Woodleaf , 10 miles northwest of Salisbury, in an area 
characteristic of the granite-diorite-gabbro complex. The large pit-type quarry is developed in plutonic rocks 
of two genetic types, gabbro and granite, both of which show apparent intrusion into the other from place to 
place in the quarry. Contacts in the granite-gabbro areas exposed in the quarry face are rather sharp, 
generally grading from one rock type to the other in a space of 1 to 2 feet. The medium gray granitic rock 
is an even-granular, medium-grained stone, containing abundant quartz, feldspar, and biotite showing strong 
parallelism. Epidote, magnetite, and pyrite are the principal accessory minerals. In the granite areas of 
the quarry, numerous well defined angular inclusions of a dark cryptocrystalline igneous rock are comomn 
and in some places constitute a textural characteristic of the intrusive granite. On the basis of megascopic 
examination and comparison with volcanic rock types found farther east in the Central Piedmont, it is be- 
lieved that the inclusions represent remnants of extensive andesitic flow rocks of the Volcanic-Slate Series 
into which the acid plutonic rocks have been intruded. A petrographic analysis of a granitic rock from the 
general area of the quarry is reported by Watson and Laney, as follows : 

". . . biotite granite in which the principal minerals, feldspar and quartz, interlock in a very irreg- 
ular and intricate fashion. . . . Plagioclase as single individuals entirely fails. . . . The feldspar is 
considerably altered principally to muscovite. . . . some epidote is noted." 

According to this description, the rock falls into the class biotite granite. 

The gabbroic rock is a dark gray, medium-grained rock showing in some places a porphyritic tendency. 
Dark silicate minerals and plagioclase are the most abundant mineral constituents. A thin section cut from 
the rock shows the following mineral percentages: 

Plagioclase , 33% 

Orthoclase 10% 

Biotite - 12% 

Pyroxene (mostly hypersthene) 44 % 

Others (titanite, sericite) 1% 

According to this analysis, the rock is placed in the class gabbro (norite). Of considerable interest in the 
examination of the thin section were the closely interlocked grains, the development of micropoikilitic struc- 
ture, and the distinctly gneissic structure of the rock. 

Structurally, the rock deposit utilized in this production of crushed stone at Woodleaf is moderately 
sheared by vertical joints, striking N. 20° E. and N. 60° E., and further broken by well developed sheeting 
planes at intervals of 2 to 15 feet. It was also observed that one of the principal directions of vertical joint- 
ing is almost always present along the acid rock-basic rock contact in the quarry; however, the sheeting 
planes are continuous across the contact zones. Throughout the quarry, quartz veins containing a consider- 
able amount of pyrite intersect the older rocks ; and veins of calcite, distinctly younger than the quartz, are 
common in highly jointed areas as joint filling. Epidote, probably associated with the formation of the cal- 
cite, occurs as a coating on open-joint surfaces and as fine stringers in the rock. 



The Commercial Granites of North Carolina 35 

The quarry is equipped with the most modern tools of quarrying, crushing, and hauling, including well 
drills, quarrymaster drills, heavy-duty Diesel trucks, belt conveyors, and primary and secondary crushers. 
The plan of quarrying over the years has resulted in the development of a pit-type quarry, covering about 
10 acres, in which a 100-foot level is the principal production level and a 150-foot level is the drainage and 
waste level. According to Mr. H. C. Burgess of the Superior Stone Company, the Woodleaf Quarry has been 
operated almost continuously since 1921. The principal product of the operation is crushed stone for use 
as concrete aggregate. 

OTHER GRANITE AREAS 

Granite areas of some significance in the production of stone in Rowan County in past years are located, 
as follows : 

Phillips Mountain: This is a low, large-diameter topographic rise, located about one mile southwest of 
Faith. As early as 1903, small quarries were operated in the area for the production of curbing from a 
light gray, medium-textured granite. No production is made in the area at present. 

Powlers Mountain : Powlers Mountain is the name given to a low dome-like mass, located 3 miles south- 
west of Faith and 9 miles southwest of Salisbury. Many years ago, some quarrying was carried on in the 
area, apparently for stone for local use. The granite is a light gray, medium-grained rock in which biotite 
or other dark silicates are almost entirely absent. 

Area of Porphyritic Granite: An area of porphyritic granite is exposed in places, beginning about 2 
miles northwest of Salisbury and extending for about 5 to 6 miles northwestward. The granite is a medium 
to dark gray and contains idiomorphic grains of orthoclase feldspar up to 2 inches across and large amounts 
of medium-grained biotite. According to Watson and Laney, a small production of crushed stone was made 
from the granite at a point 3 miles northwest of Salisbury on the Old Wilkesboro Highway. 

BASIC ROCKS 

Basic rock types have wide distribution over Rowan County, occurring as diabase and schistose dikes 
and medium-grained basic differentiate masses. The principal areas of occurrence of the medium-grained 
basic rocks are located in the vicinity of Barbers Junction, 10 miles northwest of Salisbury and extending 
southwest toward Bear Poplar, 17 miles west of Salisbury, and around Woodleaf in northwestern Rowan 
County. Basic dikes are found throughout the granitic rock areas of the county, being especially prevalent 
in areas of the granite-diorite-gabbro complex. 

GUILFORD COUNTY 

Except for limited areas of volcanic rocks in the south and schists and gneisses along the northern 
boundary, Guilford County is underlain by granitic rocks of varied texture and mineral composition, some 
of which are utilized in the production of crushed stone. (See Plate III.) The present commercial granite- 
producing areas of Guilford County are located near McLeansville, Stokesdale, Jamestown, High Point, and 
Greensboro. Noncommercial stone is produced by the State Highway and Public Works Commission at the 
Pearman Quarry in northwest Guilford County. 

THE MCLEANSVILLE QUARRY 

The McLeansville Quarry is located in east-central Guilford County, one mile west of the community of 
McLeansville and 5 miles east of the corporate limits of Greensboro. The quarry was acquired by the Supe- 
rior Stone Company in 1948, from which time large amounts of crushed stone for use as road metal and 
concrete aggregate have been produced and marketed in central North Carolina. According to Mr. P. M. 
Williams of the company, the maximum daily production during this period has ranged from 3,000 to 3,500 
tons. The quarry utilizes the most modern equipment, including percussion drilling machines for the drill- 
ing of shot holes, jackhammers, heavy-duty Diesel trucks, primary and secondary crushers, and belt con- 
veyers. ■; • 

The pit-type quarry is developed in a flat-surface mass of rocks, covered in some places by 20 to 30 feet 
of buff to reddish-brown residuum, derived from the underlying light and dark colored, medium-grained 



36 The Commercial Granites of North Carolina 

granitic rocks, basic volcanic rocks, and schistose and diabasic lamprophyre dikes. The basic volcanic rocks, 
probably of andesitic composition, occur as large,, well defined inclusions in the darker colored granitic rocks 
and are believed to represent remnants of a volcanic flow rock belonging to the Volcanic-Slate Series, into 
which granite magma was emplaced. The darker phase of the granitic rock in the quarry appears to have 
been intruded by a light gray granitic rock, containing no inclusions but intricately intermingled with the 
older material, the intricate association probably resulting from an intrusion of the acid magma into the 
incompletely consolidated darker magma. Over most of the deposit, stringers of epidote and quartz and 
cubes of pyrite, up to one inch across, are contained in both the light and dark rocks and in the schistose in- 
trusives. The diabasic lamprophyre dikes do not contain epidote, quartz, or pyrite. The rocks are rather 
moderately sheared throughout their exposure in the large shallow quarry. A thin section cut from a speci- 
men of the lighter colored granitic rock shows the following mineral composition : 

Quartz [ 20% 

Orthoclase 16% 

Plagioclase 58% 

Biotite 3 % 

Others (chlorite, apatite, magnetite, epidote, titanite) 3% 

According to this analysis, the rock falls into the class granodiorite. 

THE GUIL QUARRY 

The Guil Quarry is located 2.5 miles east of Stokesdale, 11.5 miles northwest of the corporate limits of 
Greensboro, and adjacent to N. C. Highway 65. According to Mr. Eller, quarry superintendent, the Guil 
Quarry was first opened by Guilford County for the production of crushed material for the improvement of 
county roads and was operated an unknown number of years for that purpose. Since 1948, the quarry has 
been operated by the Piedmont Quarries Company of Winston-Salem. Maximum daily production during 
this time is reported as 1,000 tons, the greater part of which is marketed as concrete aggregate and road 
metal in Guilford and surrounding counties. The quarry is developed in a low dome-shaped mass of granitic 
rock, in places covered by buff to reddish-brown residuum, which ranges in thickness from 2 to 25 feet. 
The quarry is approximately 1,200 feet in length, 300 feet wide, and 150 feet deep, making it an excellent 
example of a pit-type opening. The deposit is penetrated by binary granite dikes up to 5 inches in width, 
which show minor fault displacement at the north end of the quarry. Along the plane of faulting, the sur- 
faces of the granite are coated with a mixture of calcite and epidote, and the feldspars of the granite are 
deep red in color for 1 to 2 inches away from the plane of faulting. Minor amounts of epidote are dissem- 
inated through the rock, and 1- to 2-inch isolated or segregated areas of quartz are common in certain 
zones of the rock. The rock is light to medium-gray granite of medium texture, containing a considerable 
amount of biotite, which sometimes segregates, and a large amount of quartz. The feldspar constituent is 
composed of microcline, orthoclase, and a little plagioclase. In mineral composition and general appear- 
ance the granite is very similar to that quarried at the State Highway and Public Works Commission's Pear- 
man Quarry, located 4.5 miles to the southwest. A thin-section description of granite from this quarry can 
be found on page 37. 

THE JAMESTOWN QUARRY 

The Jamestown Quarry is located 2 miles south of Jamestown, 7.5 miles south of the corporate limits of 
Greensboro, and 0.5 of a mile north of Kivette Drive, east of High Point. According to Mr. Whitlow, ope- 
rator, the quarry was first opened by the United States Civilian Conservation Corps and was operated until 
1935, producing crushed stone for use as concrete aggregate and road metal. Since September of 1952, the 
quarry has been operated by Whitlow Brothers of High Point, and at present the operation produces a max- 
imum of 700 tons of crushed stone daily, most of which is marketed locally. 

The rock from the small bench quarry is a medium gray, even-granular granite of medium texture, con- 
taining uniformly distributed biotite and much quartz. It displays a moderate gneissic structure, showing a 
parallelism of the biotite constituent. The deposit, covered by residuum up to 20 feet thick, is intruded by 
small diabase dikes and is moderately sheared by joints, having strikes of N. 23° W. and N. The quarry 
operation is modern in every respect, being equipped with pneumatic tools, heavy-duty trucks, and a small, 
compact crushing plant. 



The Commercial Granites of North Carolina 37 

the high point quarry 

The High Point Quarry is located 1 mile south of Kivette Drive, 2.5 miles east of High Point, and along 
Two-Mile Creek. Operated by Whitlow Brothers of High Point since 1947, the quarry produces large amounts 
of crushed aggregate for the market area around the city of High Point. The bench-type quarry is devel- 
oped in a shattered body of granite, similar to that utilized at the Jamestown Quarry, but the rock contains 
more biotite and displays a strongly gneissic structure. Small amounts of pyrite and epidote are dissemi- 
nated through the rock. The buff colored residual overburden, ranging in thickness from 2 to 50 feet, con- 
tains many boulders of exfoliated granite. 

THE BUCHANAN QUARRY 

The Buchanan Quarry, owned and operated by Mr. G. C. Buchanan, is located 2.7 miles south of the 
corporate limits of Greensboro, 0.2 of a mile east of U. S. Highway 421, and adjacent to Little Alamance 
Creek. The quarry, a circular, pit-type opening having a diameter of approximately 300 feet, was opened 
in 1940 and has been operated continuously since that time in the production of crushed aggregate for the 
local market. Equipment in use at the quarry consists of a modern, compact crushing plant, wagon and well 
drills, heavy-duty Diesel trucks, power shovels, and pneumatic tools, all of the latest design. The quarry is 
developed in a gentle topographic swell, formed by rocks of the granite-diorite complex type which show 
moderate jointing and rather deep weathering. The depth of combined residuum and sap rock ranges from 
10 to 25 feet in the quarry area. The principal rocks consist of fine- to coarse-grained diorite(?) and irreg- 
ular shaped areas of younger medium-grained granitic rocks. Large blocks of an ivory colored, highly 
siliceous, fine-grained rock appear as inclusions in the diorite, and many dark lamprophyre and granite dikes, 
ranging from one inch to several feet across, penetrate the above rock units. Over most of the quarry area 
the medium- and coarse-grained rocks show moderate to strong gneissic structure and contain large amounts 
of biotite and hornblende. 

THE PEARMAN QUARRY 

The Pearman Quarry is located in northwest Guilford County, 2 miles southwest of Stokesdale and 0.7 
of a mile south of U. S. Highway 158. The quarry was reportedly opened by the State about 1937 for the 
production of crushed stone for use as road metal in Guilford and adjacent counties. At present most of 
the small production is used for improvement of secondary roads in Guilford County. The opening is a 
perfect example of a well developed bench quarry, offering an almost level access road and natural drain- 
age. Structurally, the deposit is cut into small, irregular-shaped blocks by a complex system of closely 
spaced, vertical joints and well developed sheeting planes at 2- to 5-foot intervals. The residual overburden 
ranges from 2 to 10 feet in thickness. The deposit is intersected by two prominent binary granite dikes, 
about one foot in width, which strike northeast. 

The rock is medium-grained, even-granular granite, showing a strong parallelism of the abundant biotite 
and hornblende constituents and containing a large amount of quartz and a considerable amount of finely 
divided epidote. The biotite and hornblende are most prominent in the rock when occurring together as 
almost solid bands of the two minerals. These bands appear to be relict bedding planes in the highly felds- 
pathic rock. A thin section cut from a specimen of the rock shows it to be a biotite-hornblende gneissic gran- 
ite, having the following mineral composition : 

Quartz 27 % 

Orthoclase 58 % 

Biotite and hornblende : 12% 

Others (magnetite, myrmekite, sericite, calcite, chlorite, 
muscovite, epidote) 3% 

OTHER GRANITE AREAS 

Igneous rocks or meta-sedimentary granite-gneisses have been utilized in many areas of Guilford County 
in the past, the more important localities being : 

Browns Summit and Vicinity: Browns Summit is located 8.5 miles northeast of Greensboro and 1.5 miles 
west of U. S. Highway 29. The granite in this vicinity is a light gray, medium-grained gneissic granite, con- 



38 The Commercial Granites of North Carolina 

taining abundant muscovite, biotite, quartz, and feldspar. This rock has been utilized in the production oi 
crushed aggregate in past years. A thin section of granite from a deposit 1.5 miles southeast of the town is 
described by Watson and Laney, as follows : 

"... a biotite granite . . . composed of an aggregate of quartz, microcline and orthoclase with very 
scant plagioclase. . . ." 

According to this description, the granite is classed as normal, or biotite, gneissic granite. 

Summerfield and Vicinity : Summerfield is located on U. S. Highway 220, 12 miles northwest of Greens- 
boro. Granite from many small openings in the vicinity, formerly utilized largely on a noncommercial basis, 
is a light to medium gray, even-granular, medium-grained stone which in some restricted localities has a 
porphyritic tendency. Most of the granite outcrops in this area show a marked gneissic structure. A petro- 
graphic description by Watson and Laney follows : 

". . . biotite granite of closely interknit feldspars and quartz ... biotite largely altered to chlorite 
. . . Single plagioclase individuals are absent." 

The rock falls into the class biotite gneissic granite. 

Greensboro Area: Several abandoned quarries are located within Greensboro and in the area immed- 
iately adjacent. Several of these openings were visited, but none were examined closely. In general, the 
quarries are developed in light- to medium-gray granite of an even-granular, medium-grained texture and of 
a variety similar to the medium-gray granite of the McLeansville Quarry. Work at the quarries visited was 
suspended many years ago. 

BASIC ROCKS 

Basic rocks, including diabase and schistose dikes and medium-grained differentiate masses, have wide- 
spread occurrence in Guilford County. A diabase dike, 100 feet in width and having a northeast strike, 
can be seen one mile west of Greensboro, along U. S. Highway 220 on Battleground Avenue. Other dikes of 
smaller dimension are especially prevalent in the northeast section of the county. Schistose dikes and diabase 
gabbro dikes can be seen along U. S. Highway 70 east and 420 southeast of Greensboro and in localities west 
of the city. 

FORSYTH COUNTY 

Granitic rocks containing a relatively large proportion of quartz underlie the southeastern third of For- 
syth County but are presently utilized in only one locality, at the Piedmont Quarry in Winston-Salem. The 
remaining part of the county is underlain by gneisses and schists and a narrow belt of Triassic sediments 
along the north-central border of the county. (See Plate III.) 

THE PIEDMONT QUARRY 

The Piedmont Quarry is located a few hundred feet outside the eastern city limits of Winston-Salem 
and one-half mile north of N. C. Highway 150. The area in which the large bench-type quarry is developed 
is characterized by flat-surface masses of light gray, medium-grained, slightly gneissic granite, containing 
large included masses of biotite gneiss and small dikes and veins of hydrothermal quartz and binary granite. 
Throughout the general area, residual decay is rather thin, constituting an overburden of less than 12 feet 
in the immediate vicinity of the quarry. 

The granite portions of the quarry and the large quartz-biotite gneiss inclusions are distinct units in 
the quarry walls, showing restricted gradational contacts but otherwise appearing to be separate intrusions. 
Only the presence in the granite of smaller well defined inclusions of a similar gneiss gives conclusive evi- 
dence of the included relationship of the large gneiss bodies. The slightly gneissic structure of the granite, 
showing a parallelism of the biotite constituent, seemingly represents relict bedding planes of those portions 
of the gneiss which were not completely assimilated by the granite. The presence of excessive amounts of 
silica in the parent granite magma is evidenced by large quartz segregations in both the granite and the 
gneiss. Structurally, the rock mass is moderately sheared, however only one prominent joint could be de- 
termined, it having a strike of N. 75° W. The quarry covers an area having a length of 600 feet and a width 



The Commercial Granites of North Carolina 39 

of 300 feet, and the quarry floor ranges from 75 to 100 feet below the general ground surface. According 
to Mr. L. M. Seawell, president of Piedmont Quarries, this quarry was first opened in 1929 and has been in 
continuous operation since that time. The maximum production, which is reported as 750 tons daily, is 
restricted to crushed stone of various linear sizes for use as concrete aggregate. The market area for this 
product is Winston-Salem and the immediate environs. 

A thin section, cut from a specimen of medium-grained granite from the quarry and analyzed petro- 
graphically by the U. S. Bureau of Public Roads, shows the following mineral composition : 

Quartz 39% 

Orthoclase 39% 

Plagioclase 10 % 

Microcline 6 % 

Biotite 5 % 

Muscovite 1 % 

According to this analysis, the rock is a biotite granite. In some places in the quarry, the rocks contain 
grains and crystals of almandite(?) garnet as a prominent accessory mineral. 

ABANDONED QUARRY (PIEDMONT) 

This quarry is located two miles southeast of the corporate limits of Winston-Salem and adjacent to 
N. C. Highway 109, near the confluence of Fiddler and South Fork Creeks. The bench-type quarry, covering 
about one-quarter of an acre and worked to an average depth of about 20 feet, is developed in a low dome- 
like body of massive, light gray granite which varies in texture from medium to porphyritic, the outsized 
fraction in the porphyritic phase usually consisting of grains of orthoclase up to three-quarters of an inch 
across. Biotite and muscovite are distributed evenly through all texture phases of the rock, and occasional 
segregations of quartz are also present in the exposed rock at many places. The deposit is penetrated by one 
coarse pegmatite body, containing books of biotite up to three inches across, and throughout the deposit 
small, ill-defined inclusions of biotite gneiss showing partial alteration to granite are rather numerous. The 
deposit is cut by rather closely spaced joints having strikes of N. 45° W. and N. 50° E. According to Mr. 
L. M. Seawell of the Piedmont Quarries, the granite of this deposit was first utilized in the production of 
curbstone and small building blocks for local markets, but later the quarry was the scene of considerable 
crushed-stone production. A thin-section analysis of the medium-grained phase of the rock is : 

Quartz 35% 

Orthoclase • 53 % 

Plagioclase 2% 

Biotite 9 % 

Others (epidote, zircon, garnet) 1% 

On the basis of this analysis, the rock falls into the class biotite granite. 

SNYDER PROPERTY 

Two abandoned quarries are located on the property of J. W. Snyder, 3.5 miles southwest of Winston- 
Salem and adjacent to N. C. Highway 150. The older of the quarries covers about one-quarter of an acre 
and is worked to a depth of about 30 feet. The production from the quarry was made as crushed stone for 
local road improvement, beginning about 1910. The second quarry, opened about 1920 and worked for a 
short time by Mr. Snyder, covers about three-quarters of an acre and has been worked to an average depth 
of 25 feet. When operated, production at the quarry was limited to curbing and small building blocks for 
local use. Mr. Snyder reports that the method of quarrying dimension stone at the newer quarry consisted 
of producing a lift sheet over the entire quarry area, using black powder charges and working the lift sheet 
with plugs and feathers. The granite has fair to poor working qualities. 

The granite from both quarries is medium gray in color and ranges from coarse-grained to porphyritic 
in texture, with the feldspar constituent composing the outsized grains in the rock. Like the granite at the 
Piedmont Quarry, the rock is highly siliceous and apparently contains about the same mineral composition, 
however no inclusions were seen in the exposed granite in either of the quarries. A few small binary gran- 
ite dikes intersect the deposit, and several very small stringers of epidote are present at scattered places in 
the newer quarry. 



40 The Commercial Granites of North Carolina 

the w. e. graham quarry 

The quarry is located three miles north of the corporate limits of Winston-Salem and immediately to the 
east of U. S. Highway 52. It is developed in a very dark gray to black, thin-bedded biotite gneiss, some 3 to 
4 miles away from the gradational granite and gneiss contact. The rock is fine-grained and resembles the 
biotite-gneiss inclusions contained in the granite at the Piedmont Quarry. The pit-type quarry covers about 
1.5 acres and has been worked to a depth of 100 feet. The unweathered rock, which is presently being utiliz- 
ed in the production of crushed stone, is overlain by 30 to 40 feet of dark red residuum. 

BASIC DIKES 

Diabasic and schistose basic dikes occur in a few scattered localities in the granitic rocks of Forsyth 
County, being noted in areas lying south and southwest of Winston-Salem. Such intrusions can be seen 
along U. S. Highway 158, a few miles southwest of the city. Most of the dikes are the small schistose type. 

CASWELL COUNTY 

The Main Igneous Belt of the Central Piedmont extends across southeastern Caswell County, outcrop- 
ping through the gneiss-schist complex and in large containing relict structures of the intruded rocks. With- 
in the granite areas, residual overburden attains relatively great thicknesses; consequently, outcrops are 
limited in both number and size. The production of stone in the county is confined to two quarries, a small 
State-managed operation, in the contact zone between the granite and metamorphic rocks, and a large com- 
mercial quarry, situated well into the granite-gneiss area in the northwestern part of the county. (See Plate 
III.) 

THE PELHAM QUARRY 

This quarry, operated by Lambert Brothers, Incorporated, is located at Pelham, 12 miles northwest of 
Yanceyville, in the extreme northwestern corner of Caswell County. The quarry, formerly known 
as the Collins Quarry, was reopened in 1946 and has been operated continuously, with its production being 
confined to various sizes of crushed stone for use as road metal, concrete aggregate, and railroad ballast. 
The quarry covers approximately 1.75 acres and has been worked to depths ranging from 50 to 150 feet. The 
most modern equipment is employed, including heavy-duty Diesel trucks, drills, belt conveyers, and primary 
and secondary crushers. 

The deposit in which this pit-type quarry is developed is a flat-surface mass of granite gneiss which 
has been intricately broken into irregular-shaped blocks, usually of small dimensions. Planes of jointing are, 
therefore, numerous but could hardly be divided into sets or systems. Sandy, buff-colored residuum cover- 
ing the fresh rock ranges from 5 to more than 20 feet. The rock is a pinkish-gray, rather fine-grained gran- 
ite-gneiss, displaying strong parallelism of the principal mineral constituents, quartz, feldspar, and biotite. 
A thin section, cut from a representative hand specimen, shows the following mineral composition : 

Quartz 32% 

Orthoclase and microcline 60 % 

Biotite 1% 

Others (chlorite, apatite, magnetite) 1% 

According to this analysis, the rock falls into the class biotite granite-gneiss. In thin section, the rock shows 
a strong gneissic structure with fine mosaics of quartz filling interstitial areas between larger orthoclase and 
quartz grains. Many of the orthoclase and quartz grains also show complex intergrowth, and the feldspars 
are slightly sericiticized. 

THE STATE QUARRY 

The State Quarry in Caswell County is located 6 miles northeast of Yanceyville and 2.5 miles southeast 
of N. C. Highway 62. The rocks in which the quarry is developed consist of biotite gneiss, biotite schist, mus- 
covite schist, granite-gneiss, and granite pegmatites. The light gray granite-gneiss apparently was derived 
from the incomplete assimilation of the schistose and gneissic rocks, thus accounting for its gneissic struc- 
ture. During the intrusive phases of the granite, pegmatitic fluids introduced along the schistosity and 
cleavage of the older rocks crystallized to form bands of white granitic material. Later, pegmatites have 



The Commercial Granites of North Carolina 41 

cross-cut this material. The quarry, a bench-type development, is about 75 feet deep and covers an area of 
150 by 200 feet. One prominent joint plane, striking N. 65° E., is common to both the older metamorphic 
rocks and the granite. Other planes of jointing in the deposit are obscure. The granite, which occurs not- 
ably near the floor of the quarry, is a medium-grained gray rock, showing a moderate gneissic structure and 
containing, in terms of relative abundance, feldspar, quartz, and biotite. Residual overburden, ranging from 
1 to 25 feet, overlies highly weathered schists and gneisses, but it is almost entirely absent in the granitic 
areas of the quarry, the granite showing little signs of disintegration even at the surface. 

DAVIDSON, IREDELL AND DAVIE COUNTIES 

A portion of the main body of the granitic rocks of the Central Piedmont underlies approximately one- 
half the total area of Davidson, Iredell, and Davie Counties. Volcanic rocks occupy the southern half of 
Davidson County, and gneisses and schists largely occupy the northern parts of Iredell and Davie Counties. 
(See Plate III.) Residual overburden attains relatively great thickness in the entire three-county area, and 
the scattered small outcrops of granite, excepting those adjacent to major streams, show effects of moderate 
weathering. As a result of the deep weathering of the rocks, which poses a stripping problem, no commer- 
cial granite production is made in the three counties at present ; however, some commercial dimension stone 
was produced near Mooresville, Iredell County, some years ago, and the State Highway and Public Works 
Commission is producing crushed stone from a small quarry in Davidson County. 

STATE QUARRY 

The State Quarry in Davidson County is located 9.5 miles south of Lexington and immediately adjacent 
to the Yadkin River, 1.25 miles west of N. C. Highway 8. The quarry is a pit-type opening, roughly circular 
in plan, with a diameter of 150 feet and a total depth near 50 feet. The thickness of overburden in the 
quarry area ranges from less than one foot, near the river, to more than 25 feet just a few hundred feet 
distant. The deposit is badly fractured by joints having strike directions of north and east. Crushed stone 
of various sizes is produced at the quarry for use on local secondary roads. 

The rock in the quarry area is a light pinkish-gray, massive, medium-grained granite, showing a uniform 
distribution of the biotite constituent and light pink and gray feldspars in equal amounts. A thin section, 
cut from a representative sample of the rock, has the following mineral composition : 

Quartz 1 32% 

Orthoclase and microcline 37 % 

Plagioclase 24% 

Biotite 5 % 

Others (calcite, titanite, sericite-muscovite, chlorite) 2% 

According to this analysis, the rock is near the composition of quartz-monzonite. A deep pink granite, very 
similar in physical appearance to this one, may be seen at the Davidson-Rowan county line, near the Yadkin 
River Bridge on U. S. Highway 29-70-52, southwest of Lexington. 

About one-fourth of a mile southwest of the State Quarry area, a small dimension-stone quarry was 
operated prior to 1927 for the production of paving blocks and building stone of small dimensions. The 
quarry is developed in an unjointed phase of the granite utilized in the State Quarry. 

MOORESVILLE AREA 

More than a dozen small qupvries were operated in the Mooresville area prior to and for a short time 
after 1900, the principal openings being the McNeely Quarry, one mile northwest of Mooresville, and the 
Breed Quarry, located 1.5 miles southwest of Mooresville. The general type of rock in the quarry areas is 
described by Watson and Laney in the following description of a sample of rock from the Breed Quarry : 

". . . biotite-granite. . . . Orthoclase and microcline are in nearly equal proportions, with only 1 or 
2 grains of plagioclase noted in the section. Biotite ... is present in large quantity, largely alter- 
ed to chlorite and a colorless mica." 

The rock is fine- to medium-grained, blue-gray granite of uniform texture and color. During the operation 
of the McNeely and Breed Quarries, most of the production was confined to monumental stock. 



42 The Commercial Granites of North Carolina 

davie county 

The granitic rocks of Davie County are similar to those of the Woodleaf area of Rowan County and the 
light pinkish-gray granite found in Davidson County. Outcrops are limited almost entirely to small areas 
adjacent to streams. No commercial or noncommercial granite production is made in the county at present. 

BASIC DIKES 

Dikes of basic composition are rather prevalent over the entire area bounded by Davidson, Iredell, and 
Davie Counties. Schistose and diabase dikes of basic rock may be seen best along U. S. Highway 29-70, be- 
ginning about 3 miles north of Lexington and continuing into the adjacent county. These dikes range in 
thickness from one inch to more than 100 feet, the larger ones usually showing a pronounced schistose struc- 
ture. Both the larger schistose dikes and the diabase dikes show minor displacement perpendicular to strike. 

MECKLENBURG AND CABARRUS COUNTIES 

As shown on Plate III, almost the entire area comprising Mecklenburg and Cabarrus Counties is under- 
lain by granite and related rocks of the Main Igneous Belt, however the commercial development of these 
rocks never has been attempted on a large scale. At present, the only granite production in the two counties 
is made in the form of crushed stone at a small State quarry in Mecklenburg County. The lack of commer- 
cial utilization of the rocks in this area can probably be attributed to the generally thick residual overburden 
and the lack of uniformity of physical characteristics of the various rock types. 

MECKLENBURG COUNTY 
THE CHARLOTTE AREA 

Within the present corporate limits and the vicinity immediately adjacent to Charlotte, granite was 
quarried from several small openings around 1900, but today these openings have been filled or are grown 
over by vegetation. One such quarry, "The City Quarry," described by Watson and Laney as being the larg- 
est opening in the county, produced crushed granite for use on the streets of Charlotte. From the descrip- 
tions of other openings in the Charlotte area, the granite from this quarry seems typical of the rocks in the 
general environs. A microscopic analysis of this stone is given by Watson and Laney, as follows : 

"... a biotite granite of a fine textured complexly interlocking aggregate of feldspar and quartz. 
Potash feldspars, orthoclase and microcline, and microperthitic intergrowths, with very little pla- 
gioclase compose the feldspathic constituent. The biotite is irregularly distributed through the sec- 
tion. ... A few scattered grains of magnetite occur. . . ." 

The principal areas in Mecklenburg County in which the granites seem most likely to have potential 
commercial value are the Charlotte area, the area in and around Davidson in the northern part of the county, 
and a small area 4 miles south of Newell, a community about 5 miles northeast of Charlotte. 

STATE QUARRY 

A State-operated quarry, located 9 miles north of Charlotte and 1.5 miles southwest of Huntersville, 
produces crushed stone for secondary road improvement in Mecklenburg County. At present, it is the only 
granite operation in the county. The pit-type quarry is developed in rocks of the granite-diorite complex, 
in which both the granite and diorite units contain well defined schist inclusions and show penetration by 
basic dikes and stringers of younger epidote and binary granite. Joints, having strikes of N. 40° W. and 
N. 10° W., break the rocks into blocks of rather small dimensions. Residual overburden in the quarry area 
ranges from 5 to 15 feet in thickness. The granite, slightly pinkish-gray in color, is an even-granular, med- 
ium-grained stone, containing abundant quartz, orthoclase and plagioclase feldspars in about equal propor- 
tions, and considerable biotite which tends to segregate. The granite appears to intrude the darker colored 
diorite. 

CABARRUS COUNTY 

Except for a few small quarries operated many years ago in the vicinity of Concord, the granites of 
Cabarrus County have not been worked commercially. Of the many types of granitoid rocks found in Cabar- 



The Commercial Granites of North Carolina 43 

rus' County, including normal granite of a fine to porphyritic texture, quartz-monzonite, diorite, and gabbro, 
perhaps the most unusual is a coarse-grained augite-syenite which outcrops in the western part of the 
county. The syenite is exposed as immense boulders, forming an elliptical pattern, beginning at the village 
of Harrisburg in southwestern Cabarrus County, swinging northwestward for about 4 miles, turning east for 
2 miles, and trending southeast to a point a mile east of Harrisburg. The width of the exposed syenite 
varies from less than one-fourth of a mile to slightly more than a mile. The "ring" of syenite encloses an 
area of gabbroic rocks approximately 4 miles in diameter. The syenite is composed largely of outsized grains 
of potash feldspar, about 15 percent of the ferromagnesian mineral augite, and a minor amount of dark- 
colored accessory minerals. The overall color of the rock is light bluish-gray. A thin section analysis by 
Watson and Laney reveals the following mineral composition and physical characteristics of the rock : 

"... a coarse-textured, augite-hornblende-biotite syenite composed very largely of feldspar with 
slight quartz, and the accessories mentioned. The feldspars are orthoclase, microcline, microperthit- 
ic intergrowths and subordinate plagioclase (oligoclase). . . . Green augite (diopside) is the prin- 
cipal ferromagnesian silicate. Hornblende of green color exceeds biotite in amount." 

This rock was being utilized in the production of ballast about 1903, however no attempt at quarrying it for 
use as monumental or buiuding stone has been made. 

Other outcrops of the granite and related rocks of Cabarrus County are found at widely scattered places, 
however none are of sufficient importance to be discussed here. 

BASIC ROCKS 

Basic rocks of both even-granular medium texture and fine-grained dike material have widespread occur- 
rence in Macklenburg and Cabarrus Counties. In Mecklenburg County, basic rocks are most prevalent in 
areas east of Charlotte and in the vicinity of Davidson. Basic rocks in Cabarrus County are represented by 
diabase and schistose dikes in widespread areas east and west of Concord and as medium-grained dioritic 
rocks in the southwestern part of the county. 

GASTON, LINCOLN, AND CATAWBA COUNTIES 

Rocks of the Main Igneous Belt underlie the central and eastern parts of Gaston County and the eastern 
portions of Lincoln and Catawba Counties, (Plate III), however no commercial granite has been produced in 
the area except for minor amounts from a few small openings in the vicinity of Gastonia. These small quar- 
ries, operated many years ago, produced small quantities of dimension stone in the form of sills, machinery 
bases, rough-tooled monuments, and some crushed stone, all of which were marketed in the Gastonia area. 
Most of the granite was quarried from large boulder and ledge-like outcrops, which are quite common in the 
central part of the county especially in and around Gastonia and which also represent the largest exposures 
of workable granite in the three-county area. A thin-section analysis of a typical granite from Gaston 
County is described by Watson and Laney, as follows: 

"The rock is a biotite granite in which the potash feldspars, orthoclase and microcline, are present 
in nearly equal amounts. ... In several of the sections plagioclase failed entirely, while in others 
only a few scattered finely striated grains were noted. . . . Biotite is of the usual kind and is large- 
ly altered to chlorite. . . . The usual microscopic inclusions of apatite and zircon occur." 

* 

Most of the granitic rocks of the three counties, especially those noted near their contact with the gneisses 
and schists to the west, show some parallel growth of the mafic constituent and some evidence of recrysal- 
lization of quartz. 

OTHER COUNTIES 

Other counties in the Central Piedmont in which granite and related rocks occur include Alamance and 
Person, both of which are of little importance relative to the production of commercial or noncommercial 
granite. Rockingham County, in the northern part of the Central Piedmont, lies entirely out of the Main 
Igneous Belt but has been an important producer of crushed stone in the past, the production coming from 
a quarry developed in a siliceous gneissic rock. 



44 The Commercial Granites of North Carolina 

ALAMANCE COUNTY 

Most of the granitic rocks of Alamance County are complexly associated with rocks of the Volcanic-Slate 
Series, into which they were emplaced ; and, in turn, this complex has been intruded by large dikes of basic 
rock and innumerable small aplite dikes. The decay of the granite and associated rocks has progressed to 
such an extent as to render outcrops of fresh rock rare, except along major drainage. A thin section, cut 
from one such outcrop of a medium-gray, large-grained granite exposed along Reedy Fork Creek in the 
village of Ossipee in northwestern Alamance County, shows the following mineral composition : 

Quartz 20 % 

Orthoclase 51% 

Plagioclase 17% 

Biotite 8 % 

Others (mostly epidote with minor amounts of apatite, 

magnetite, and sericite) 4% 

This analysis indicates that the rock is near the composition of normal granite, however it is apparent that 
it has suffered considerable alteration as manifested by the large amounts of epidote included in the mineral 
composition. Of considerable interest in the examination of the section was the abundance of zoned plagio- 
clase feldspar. Prior to 1906, the granite from this ledge-like outcrop along the creek was worked to sup- 
ply rough building stones in the immediate vicinity of Ossipee and Altamahaw. 

PERSON COUNTY 

The production of granite in Person County has been limited to one large State-operated quarry, locat- 
ed one-half of a mile east of Roxboro. At present, the quarry is abandoned. This quarry, a bench-type 
opening, is developed in a light pinkish-gray, mostly large-grained granitic rock deposit, which forms a 
rather prominent topographic rise trending north for a distance of approximately a thousand feet. The 
rock shows signs of considerable shear, being broken into small irregular blocks by planes of jointing, strik- 
ing N. 42° W., N. 10° E., N. 77° W., and N. 33° W. Sheeting planes at intervals of about one foot are well 
developed over the entire quarry, which covers an area of about one-half of an acre and has been worked to 
a depth of 40 feet. Residual overburden in the quarry area ranges from 1 to 15 feet in thickness. The 
rock body contains many small quartz veins and numerous inclusions of dark volcanic rock. Orthoclase 
feldspar is the principal constituent of the rock, followed in abundance by the included volcanic rocks, 
quartz, and biotite. 

ROCKINGHAM COUNTY 

Some years ago, large amounts of crushed stone were produced at a quarry developed in siliceous gneiss 
near the village of Stacey, in east-central Rockingham County. This quarry, now abandoned, offers an ex- 
cellent opportunity for further development, especially at the north end where water has not flooded the 
opening. The rock is a hard, well bedded, highly siliceous gneiss containing abundant quartz, much feld- 
spar, small amounts of biotite, and scattered dark accessory minerals. The deposit is strongly sheared. 

GRANITES OF THE WESTERN PIEDMONT 

The Western Piedmont division of the Piedmont Plateau is mostly underlain by pre-Cambrian gneisses 
and schists, penetrated in some places by granitic rocks which tend to form narrow northeast trending belts. 
Sedimentary rocks of Triassic age occupy relative lowlands in parts of Stokes, Davie, and Yadkin Counties, 
in the northeastern part of the region. The area comprising the Western Piedmont is bounded on the east 
by the Main Igneous Belt of the Central Piedmont and the eastern line of Stokes County; on the west, by 
the Blue Ridge escarpment, and by Virginia and South Carolina, respectively, on the north and south. (See 
Plate IV.) 

Outcrops of granite in the Western Piedmont generally are limited to scattered boulders and flat-surface 
outcrops; however, several large "stone mountains" stand as barren granite monadnocks, especially in the 
northern half of the division. Residual decay in the granite areas is similar in composition and color to the 



The Commercial Granites of North Carolina 45 

material of the other granite regions of the State and is equally as thick. All, or a portion, of 17 counties 
comprise the Western Piedmont area, including the present or former granite and granite-gneiss producing 
counties of Surry, Wilkes, and Yadkin. At present, commercial granite production is limited to the famous 
Mt. Airy quarries, the largest single dimension-stone operation in the State and among the largest and most 
modern in the Nation. The granite potential of this region can be considered unlimited. However, the 
massive character of the granite will constitute much difficulty should quarrying operations for crushed 
stone be undertaken in some areas. 

SURRY COUNTY 

The principal occurrences of granite in Surry County form two narrow belts, trending northeast, across 
a part of the eastern half of the county. The remainder of the county is underlain by various types of 
gneisses and schists, which contain numerous small pegmatitic intrusives and a few small diabase dikes. 
In the igneous belts, the largest of the rather scarce outcrops of granite occur as boulders and low flat-sur- 
face masses, showing most often an advanced stage of decay which renders the stone useless as a source 
either of crushed or dimension granite. The notable exception to the deep weathering exhibited by the gran- 
ites is the immense, gently sloping outcrop of fresh granite exposed for about live thousand feet along the 
crest of a rather conspicuous hill, one mile northwest of Mt. Airy. Quarrying on an extensive scale has 
been carried on in this area continuously since 1904 by the North Carolina Granite Corporation and for 15 
years prior to that time by Thomas Woodroffe and Sons and The Mt. Airy Granite Company. 

THE NORTH CAROLINA GRANITE CORPORATION (MT. AIRY QUARRIES) 

The quarries of the North Carolina Granite Corporation are located over an area covering more than 
a hundred acres atop and on the gentle slope (12°) of a large dome-like outcrop of unjointed, slightly 
gneissic granite, having areal dimensions approximating one mile by one-half of a mile. The quarries con- 
sist of several working areas devoted exclusively to the quarrying of dimension stone and one large area in 
which stone is quarried for crushing in a plant equipped to produce poultry grit from the stone. 

The dimension-stone areas at Mt. Airy, unlike other dimension granite quarries in North Carolina, 
have very little depth from the top surface of the granite to the working surface. This type quarry devel- 
opment has resulted from the working of layers, or sheets of granite separated from the main mass by the 
induction of sheeting planes at 6, 8, or any desired number of feet below the surface of the rock body and work- 
ing these layers of granite until exhausted. Quarry development such as this is greatly facilitated by the gentle 
slope of the rock from the uppermost outcrop area to the base of the exposure. In the case of the Mt. Airy 
quarries, lift sheets, or layers, of granite are produced by cleaving the stone at a depth below the surface 
comparable to a desired thickness of the rough block and splitting along vertical planes, using feathers and 
wedges, to the desired horizontal dimensions. Rough blocks are hoisted onto quarry cars for removal to the 
cutting and finishing sheds. After a complete lift sheet has been worked off, another may be produced in 
the same area and worked similarly. Each quarry may produce blocks of varying widths and uniform 
thickness, so that, an order for stone of a desired width are available for transport to the cutting sheds 
for custom splitting into blocks of less thickness than those quarried. Thin slabs of granite also may be 
produced at the quarry from a lift sheet of less thickness than the usual 6 or 8 feet. This method of quar- 
rying sheets is essentially one of peeling off layers of granite as needed. The creation of artificial sheeting 
planes, or bottom joints, in the Mt. Airy quarries will be discussed in the section of this report concerned 
with quarrying. 

The blocks of granite from the several quarries are cut, surfaced, and finished in plants located at the 
base of the granite hill. These plants, among the largest and most modern in fhe Nation, are capable of 
turning out granite in any form, polished or rough-cut as the market demands. Some of the various equip- 
ment available for finishing the granite are gang and diamond saws of the latest design, surfacing machines, 
contour machines, automatic polishers, and precision instruments employed in the shaping of statues and 
memorials of various designs. (See Figure 4.) The principal dimension-stone products from the Mt. Airy 
quarries include mausoleums, bridge construction stones, statues, architectural stone, and curbing. Of these 
products, the company leads the Nation in output of mausoleums, ranks second in the production of bridge 
construction stones, and is a leading producer of the other products, especially architectural stone and cus- 



46 



The Commercial Granites of North Carolina 



tom-made curbing. Production figures furnished by Mr. J. P. Frank, president of the company, show that 
3,600 carloads of granite were shipped from the quarries in 1952. This figure includes 1,200 carloads of 
poultry grit of the various sizes produced at the company's crushing plant. In comparison with the 1952 
production, 135 carloads of granite were shipped from the quarries in their first year of operation during the 
year 1889 to 1890. 




Figure 4. Cutting Granite With Diamond Saws, Mt. Airy Quarries, Surry County 

The crushed-stone quarry is much the same as other bench-type quarries in North Carolina. Granite is 
dislodged from the walls of the quarry by dynamite charges, set into drill holes of large diameter. Shots 
are detonated in milli-second, delayed-action sequence to produce the best possible fragmentation. Large 
blocks of stone remaining after a shot are reduced to the desired size by the use of a one-ton, drop-ball 
setup. This method of secondary fragmentation has proved a most effective and time-saving method at Mt. 
Airy and could well be put into use in other crushed-stone quarries across the State. The broken stone is 
moved by truck to a well equipped crushing plant, a few hundred feet from the quarry, and fed into crush- 
ers. From the crushers, the stone moves through a series of screens of various sizes, designed to retain the 
crushed granite in the five-size classes in which the rock is sold as poultry grit. The crushed granite, sacked 
and sold under the trade name of "Grani-Grit," has found a large market in many parts of the United States. 
Crushed stone from this plant is also marketed as concrete aggregate. 

Mt. Airy granite is a very light gray to almost white, medium-grained stone, composed of much feldspar, 
quartz, biotite, and exceedingly small amounts of apatite, zircon, and epidote. Except for the biotite, which 
tends to segregate, the mineral constituents of the granite are distributed very uniformly, thus presenting a 
stone of unusual beauty and adaptability. This stone is widely known as a white granite and has found many 
uses for which hard, durable stones of light color are desired. A thin section, cut from a representative 
sample of Mt. Airy granite, shows the following mineral composition: 

Quartz _ 26 % 

Orthoclase 32 % 

Plagioclase ; 33 % 

Biotite _ ,8% 



Others (apatite, zircon, muscovite, chlorite, and epidote) .. 1 



7° 



In thin section, this stone, a quartz-monzonite, shows a slightly gneissic structure, minor kaolinization of the 
feldspar constituent, and some grains of microperthite. A chemical analysis of the stone may be seen on 
page 3, in column 4 of Table I. 



OTHER AREAS 

Granite occurs in other counties of the Western Piedmont in much the same manner as in Surry County ; 
however, it is more or less gneissic, depending upon the degree of pressure metamorphism to which the rock 
bodies have been subjected or the degree to which the structures in the intruded gneissic rocks have been 



The Commercial Granites of North Carolina 47 

retained by the granite. Notable areas of granitic rocks in the Western Piedmont include: (1) parts of the 
northern third of Stokes County, (2) a narrow area across central Yadkin County, (3) an elliptical-shaped 
area in Cleveland County which extends into northwestern Gaston County, and (4) an elongated body of 
granite underlying parts of southeastern Polk County and southwestern Rutherford County. (See Plate 
IV.) Smaller areas of strongly gneissic granites underlie parts of Wilkes, Catawba, Caldwell, and Alexander 
Counties. In most of the above areas the granitic rocks are broken into small irregular blocks by profuse 
jointing and are usually overlain by great thickness of residual soil. 

Residual masses of granite or granite-gneiss, often called "stone mountains," are rather prominent in 
the Western Piedmont. Two of the largest are described by Watson and Laney, as follows : 

Alexander County : "Rocky Face Mountain, which is located about 6 miles northeast of Taylorsville, 
... is an elongated dome-shaped mass of granite-gneiss rising to an elevation of not less than 500 
feet above the surrounding plain and measuring about 4 miles around the base ... a residual of 
biotite granite-gneiss of light gray color and medium texture made up of alternating dark and light 
colored layers. . . . The banding is of irregular thickness though generally averaging thin. . . . 
The strike of the joint planes observed was N. 30° E. and N. 80° E." 

According to the thin-section analysis of this stone, it is a biotite granite-gneiss. 

Wilkes County : "Stone Mountain, the most prominent one of the granite residuals, is an oval shaped 
mass of granite, 500 to 600 feet high and measuring 3 to 4 miles in circumference, at the base. . . . 
The rock is a light gray, nearly white, medium-grained, biotite granite of slightly coarser texture 
than the Mt. Airy granite in Surry County, which it closely resembles in color and other properties 
... it shows a few segregated areas of black biotite, which become somewhat frequent in certain 
portions of the rock. . . . Like the Mt. Airy granite, it is nearly free from joint-planes, not more 
than half a dozen joints being observed in the entire residual. These had a strike of N. 45° E. and 
N. 45° W." 

Other residual granite masses somewhat smaller than those described above are located along the boun- 
dary line between Wilkes and Alleghany Counties. These masses retain the oval shape of the "stone moun- 
tains" and appear to have mineral compositions similar to the larger residuals. The "stone mountains," 
although representing large volumes of granitic rock, are unsuited for quarry development of any type. The 
rather steep slopes of the "mountains" and the general lack of uniformity of color and texture render the 
rocks useless as a source of high-quality dimension stone, while the massiveness of the rock bodies dismisses 
them as good sources of stone for crushing. 

Some commercial quarrying for crushed stone has been conducted in the past in the vicinity of North 
Wilkesboro, Wilkes County; Hickory, Catawba County; and Yadkinville, Yadkin County, in areas underlain 
by granite-gneiss, however no regularly operated quarries are known in these areas at the present time. 
From time to time, the North Carolina State Highway and Public Works Commission utilizes granite-gneiss 
in the production of crushed stone in some parts of the Western Piedmont, but these operations are usually 
small and of a temporary design. 

GRANITES OF THE BLUE RIDGE 

The Blue Ridge, smallest and westernmost physiographic division of the State, contains several granite 
and granite-gneiss areas, however no commercial granites are produced in the region at present. The prin- 
cipal granite and granite-gneiss bodies, representing a rather complete penetration of older gneisses and 
schists, underlie parts of Transylvania, Jackson, Macon, and Clay Counties. Like the granite areas in the other 
regions of the State, these bodies tend to form more or less narrow belts which lie along northeast-southwest 
trending axes. Other granitoid rocks are found in several other counties in complex association with older 
metamorphic rocks, but these occurrences are of little significance in a report of this type. An interesting 
large-grained to porphyritic granitic rock, or "alaskite," underlies a rather extensive area of Mitchell and 
Yancey Counties and is utilized extensively in the ground feldspar and mica industries in that section. This 
rock has been classified mineralogically as a "leucogranodioritic fine-grained pegmatite" by Parker, (p. 9, 
1952). 

Gneisses and schists of the mica and amphibole types are the most abundant rocks in the Blue Ridge, at 
times being important in the production of crushed stone. However, natural gravel from flood plains and 



48 



The Commercial Granites of North Carolina 




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The Commercial Granites of North Carolina 49 

intermittent stream channels and crushed limestone from several quarries are utilized largely as aggregate i 
and road metal because of the comparative ease in obtaining the materials. Other rock types,' quarried on 
a minor scale in the region, include quartzite, slate, and shale. 

Since rocks of the massive granitic type are relatively rare in the Blue Ridge, the unlimited amounts of 
metamorphic rocks offer the largest and most available sources of stone for use either as dimension or 
crushed stone. In many places these rocks are sound and of a color requisite for use as dimension stone, 
especially for rough construction and bridge building, and the availability of stone for crushing is equally 
as favorable. Quarries utilizing gneisses or schists have been operated in Buncombe and Henderson Coun- 
ties, but none are known to be operating at the present time. 

Due to the lack of commercial granite production in the Blue Ridge, a minimum of work was done in the 
region, and most of the following data were compiled from the report by Watson and Laney and folios pub- 
lished by the United States Geological Survey. Only the more important occurrences are described, and they, 
very briefly. 

Swain County: A medium- to coarse-textured, light gray biotite granite-gneiss is exposed 1.5 to 2 miles 
west of Bryson City along the deeper railroad and highways cuts. This gneissic rock, distinctly intrusive 
into mica schist, shows a lineation of the mineral constituents in a direction opposed to that of the schist. 
According to a thin-section analysis, the rock has a mineral composition comparable to normal, or biotite, 
granite-gneiss. The deposit may prove of some value as a source of stone for crushing. 

Henderson County: An abandoned quarry, covering about a quarter acre, located 1.7 miles north of 
Hendersonville and 0.5 of a mile east of U. S. Highway 25, has been developed in an unusual augen-gneiss of 
a mineral composition approximating granite. This distinctive rock type underlies a rather extensive area 
in central and southern Henderson County and parts of eastern Transylvania County. It is a medium gray, 
medium-grained granite-gneiss, containing large, elongated (elipsoidal) phenocrysts of potash feldspar lying 
parallel to the well developed schistosity. The quarry was formerly operated for the production of railroad 
ballast, but blocks of stone 4 by 8 by 10 feet are reported easily quarried and to have good splitting qualities. 
A stone such as this would be admirably suited to interior or exterior dimension work wherever unique 
stone is required. 

Transylvania County: Granitic rocks showing strongly gneissic structure are exposed in several scat- 
tered localities along the western boundary of Transylvania County but are not known to be worked in any 
locality at present. Considering the irregular character and complex jointing of these rocks, it is doubtful 
that they can be utilized except as a source of stone for crushing. 

Clay and Macon Counties : Small areas of Clay and Macon Counties are underlain by granite-gneisses, 
forming a narrow belt trending northeast across a part of these counties. The principal rock type is a typical 
fine-grained, light gray biotite-granite gneiss, varying from slightly gneissic to extremely schistose. Jointing 
is fairly well developed and often widely spaced. This rock may prove useful as a source of crushed stone in 
some areas should market demands merit its exploitation. 

Other Areas: Other less notable areas of granite and granite-gneiss occurring in the Blue Ridge are 
found in Madison County near Hot Springs, the southern part of Jackson County, and parts of Watauga and 
Ashe Counties ; however these rocks are most often complexly intercalated with older gneissic and schistose 
rocks and will, therefore, prove of little or no commercial value. 



50 



The Commercial Granites of North Carolina 



PROSPECTING, EXPLORATION, AND QUARRYING 

DIMENSION STONE 

In prospecting for granitic rocks of dimension-stone quality, it is advisable to consider the conditions of 
occurrence, as follows: (1) size and shape of the deposit, (2) topographic expression, (3) spacing and fre- 
quency of joints, including sheeting planes, (4) overburden and depth of weathering, and (5) uniformity of 
texture and color. 

PROSPECTING AND EXPLORATION 

Size of Deposits: Magmas, from which granites and related rocks are derived, are intruded from un- 
known depths into the crustal portion of the earth in large masses, so that outcrops and shallow-lying bodies 
of granite represent the parts of deep-seated intrusions implaced into portions of the crust nearest the sur- 
face of the earth. Therefore, any outcrop, regardless of areal extent, can be considered generally as bottom- 
less, and stone can be removed from a deposit so long as it is economically feasible to quarry. 

Topography: The topographic expression, or attitude, of a rock deposit often influences greatly its value 
as a potential source of commercial stone. Broad, flat occurrences of granite necessitate vertical descent into 
the deposit and a horizontal expansion of the initial opening. Openings of this type are referred to as pit 
quarries, and production from this type of quarry in most instances is expensive or even prohibitive, due to 
a delayed and smetimes low return from original investment. 

Many granite deposits occur as dome-shaped masses, rising above the general level of the surrounding 
terrain and permitting the development of wide, shallow quarries with easy access and natural drainage. 
In rock masses displaying the dome-like attitude, the production of stone is facilitated without working 
downward from the surface. Generally, openings are made in any flanking face of the "dome" and worked 
more or less horizontally and to a much lesser extent vertically. Such developments are called shelf or bench 
quarries and are seldom deep unless restricted by. property lines or by improvement of the rock at depth. 
Figure 5 shows a cross section of a pit-type and a bench-type quarry. 




PIT QUARRY 





BENCH QUARRY 



Figure 5 : Idealized Cross Section of Pit and Bench-type Quarries 

Joints: The position and direction of quarry walls is, in most instances, governed by the joint systems. 
A prominent joint plane usually constitutes a heading, or quarry wall, along which the initial opening is 
deepened and expanded horizontally. The joint systems at right angles to each other constitute the ideal 
condition necessary for the development of a rectangular-shaped quarry, and dimension stone taken from 



The Commercial Granites of North Carolina 51 

such a quarry is itself roughly rectangular. Blocks of geometric shape are tooled more easily ; thus, the de- 
velopment of a quarry facilitating the production of rectangular blocks aids in the lowering of operating 
costs. The spacing of both vertical and bottom joints determines the thickness of dimension stone and 
should be considered critically in prospecting for dimension-stone quarry sites. A close spacing either of the 
vertical or bottom joints dismisses from consideration a deposit for quarrying dimension stone of large size. 
Likewise, the absence of extremely wide spacing of joints may render the deposit unusable unless the stone 
is of exceptional quality. Sheeting planes 10 to 30 feet apart and vertical joints 10 or more feet apart are 
considered ideal for dimension-stone quarrying. 

Overburden : In most granite-quarrying areas in North Carolina it is necessary to remove residual over- 
burden preparatory to producing dimension stone. The decayed rock is removed by mechanical methods, in- 
cluding dragline scrapers or excavators, power shovels, and tractor excavators. Hydraulic methods can be 
used if sufficient water is available and the site is provided with favorable waste-disposing areas, affording 
natural drainage. Completely decayed residual overburden. ranges from less than one foot to 20 or more feet 
in thickness and is generally underlain by partially decayed rock unsuitable for marketing. This material 
must be removed by hand methods or carefully controlled blasting. 

Color and Texture: Color and texture in granite deposits should be consistent both laterally and ver- 
tically in order to assure uniformity in the marketed product. 

QUARRYING 

Present-day methods employed in the separation of large blocks of granite from the quarry wall and 
further subdivision of the large masses are varied and are discussed here in a general way. Specific altera- 
tions in the general procedures as used in North Carolina quarries are mentioned in the descriptions of indi- 
vidual quarrying areas. 

In the separation of blocks of granite from a deposit or into stones of smaller dimensions, one of two meth- 
ods — blasting or wedging — is generally used. In the separation of a block from the quarry wall by blasting, 
small diameter shot holes are drilled to a depth slightly above the sheeting plane and along a straight line for 
the linear distance desired. The spacing of the holes is determined by prior experience, but they are nor- 
mally drilled a foot or two apart. The holes are charged slightly with black powder, tamped lightly, and 
detonated simultaneously. The simultaneous exploding of the powder charges results in an even distribution 
of the shot through the stone. Care must be taken during the separation to use the exact amount of powder 
necessary for the fracture, since use of an excess of the explosive may cause a shattering of the block or a weak- 
ening of it by the creation of microscopic or incipient fractures. The shot holes for this type breakage are 
drilled with pneumatic drills, and a reaming tool is sometimes used to cut grooves in the shot holes in line 
with the direction of desired splitting to facilitate the fracturing. 

In most quarries the use of powder for the separation of block granite has been replaced by mechanical 
wedging methods. The most common of these methods or techniques is known as plug and feather wedging. 
The tool used to accomplish the separation consists of two half -rounded steel bars, called feathers, on each 
side of a hard steel chisel, known as the plug, extending above the feathers. A break in granite is produced, 
using this method, by drilling a series of plug holes 4 to 6 inches in depth and 6 to 18 inches apart along the 
line of desired fracture, using a hard steel bit. Plug and feather tools are then placed into the holes and the 
plugs are struck successively until the wedging pressure of the feathers is sufficient to produce a failure in the 
stone. Usually, a little time is allowed between the sledging of the plugs for the pressure exerted by the 
feathers to be distributed evenly along the line of holes. Well developed rift and grain aid immeasurably in 
plug and feather fracturing, and fortunately the rift usually parallels the major joint system along which the 
opening is developed in granite deposits. Figure 6 shows the setup of a plug and feather wedge preparatory 
to splitting. If it is desirable to produce a break parallel to the hard way (against rift or grain), "foot" 
holes 1 to 11/2 feet deep are drilled between plug holes lVo to 4 feet apart and the same procedure used as in 
"rift" fracturing. 



52 



The Commercial Granites of North Carolina 





Figur 



Plug and Feather Splitting of Granite 
(J. A. Logan Quarry, Faith) 



A method known as broaching or channelling also is used for making breaks in granite against rift and 
grain. This method involves the drilling of closely spaced holes along the poposed line of fracture, using 
a quarry or channel bar equipped with a rounded, hard steel drill. The holes are usually about 2 inches in 
diameter and are drilled vertically until they intersect the sheeting plane. The undrilled granite, or webs, 
remaining between the holes is removed by replacing the rounded bar with one terminating in a wedge and 
drilling the webs vertically to the point of intersection with the sheeting plane. The second step completes 
the separation of the block from the quarry wall. Figure 7 shows a quarry or channel bar in a working 
position. ._ 




Figure 7 : Channel Bar in Working Position 
(J. A. Logan Quarry, Faith) 

Large thin blocks of granite are obtained by drilling a line of holes 6 inches apart to almost the full 
depth of the desired block and using plugs and feathers and channel bars in the same manner as described 
above. 

In the absence of natural sheeting planes, the vertical thickness of granite is determined by artificial 
breaks in the granite, accomplished by using the lift method. An artificial sheeting plane or lift is pro- 
duced in the following manner : In the approximate center of the sheet to be lifted, a 2- to 3-inch diameter 
hole, called the lift hole, is drilled to a depth of 6 to 10 feet, depending on the maximum thickness of stone 
required, and small amounts (V2 to 1 lb.) of black powder are successively detonated in the bottom of the 



The Commercial Granites of North Carolina 53 

hole until a crack is extended for a distance of 75 feet, more or less circumferential to the hole. A pipe is 
then cemented into the hole and air, compressed to 70- to 80-pound pressure, is gradually admitted until the 
crack is extended in all directions and appears at a point on the slope surface of the deposit. A peripheral 
break of say one acre requires about half an hour as against 10 to 12 days for an equal extension of the crack 
using powder charges. Care must be taken during the process to control carefully the induction of com- 
pressed air into the cavity ; otherwise, suddenly increased pressures will turn along a vertical plane of weak- 
ness in the rock and come to the surface prior to the lifting of the sheet over the desired area. The use of 
compressed air in the extension of the powder-produced, artificial sheeting plane is not always necessary, 
especially during the hottest of the summer months. During the cleaving procedure in the summer, the 
weight of .the overlying granite, attempting to attain gravity equilibrium by sinking into the powder-pro- 
duced cavity, exerts sufficient horizontal strain or lift action in the granite to extend the crack naturally. 
For reasons unknown but perhaps through the aid of natural expansion of the rock in response to heat, the 
production of a sheeting plane by the described method is best accomplished during the summer months. It 
is doubtful that a sheet would cleave during extremely cold weather. Lifts over small areas are completed 
entirely by the use of black powder and usually cover only 1,000 to 2,000 square feet. Subdivision of the lifted 
sheet is done by the plug and feather method, as described above. 

Removal of Stone from Quarry: The removal of dimension stone from the quarry, or the transfer to 
spur railroad or motor trucks, is accomplished by the use of derricks equipped with steam or electrically 
operated hoists. The derricks are constructed either of steel or wood and are generally capable of handling 
blocks weighing up to 50 tons. Electrically powered steel derricks are in general use in the dimension-stone 
quarries of North Carolina. 

CRUSHED STONE 

A plan for prospecting and exploration for crushed stone sources can be carried out in much the same 
fashion as one for dimension stone, though physical and structural requirements of deposits are much less 
rigid. Critical analyses of size, shape, topographic expression, and overburden are parallel requisites. The 
spacing and frequency of joints are considered in a different manner, and color and textural properties are 
of little significance. Joints serve to best advantage when closely spaced and free from filling by fine-grain- 
ed residual or clastic material, which operates as a cushioning medium to the shot. A close spacing of open 
joints facilitates good fragmentation at a minimum expense, thus preventing time-consuming secondary frag- 
mentation. Quarries either of the bench or pit types developed in highly jointed rock deposits are called 
boulder quarries, and most crushed stone operations are developed in such. areas. 

The presence of widely spaced vertical joints is as detrimental in crushed stone quarry operations as close- 
ly spaced ones in dimension-stone quarries. Widely spaced fractures necessitate an increase in the use of 
blasting powder for primary fragmentation, and an additional increase in cost may be incurred for secondary 
shooting of large unbroken blocks. Large blocks of stone remaining after the initial shot are reduced fur- 
ther in size by "adobe" shooting, "block-holing," or the drop ball. Block-holing is used most frequently in 
North Carolina quarries, although it is generally more expensive than the adobe or the drop-ball methods. It 
is accomplished by drilling one or more small-diameter holes with hand-held drills and detonating a powder 
charge in each hole. 

Perhaps the prime economic consideration in crushed-stone exploration and quarrying is the proximity 
to market. Seldom, if ever, are the physical and structural characteristics of any rock deposit ideal for the 
development of the deposit, but a nearness to market and a perennial demand for crushed stone frequently 
offset the increased costs in the quarrying of rock of otherwise undesirable occurrence. 

For successful operation, the type of quarry development for the removal of stone for crushing should 
be similar to the most efficient in dimension-stone quarrying. Generally, openings are made into "domes," 
deepened vertically for 50 to 200 feet, and worked horizontally until restricted by property lines. The rather 
rapid deepening of a crushed-stone quarry is necessitated by the removal of large tonnages in a comparatively 
short time and the need for high quarry faces from which to dislodge large amounts of rock to feed continu- 
ously operating crushers. In the shooting of characteristic steep faces in rock quarries, several rows of 
holes — either parallel or staggered — are drilled to depths slightly below the floor of the quarry, charged with 



54 The Commercial Granites of North Carolina 

powder of great strength, and detonated either simultaneously or in milli-second, delayed-action sequence. 
Shot holes of fairly large diameter (6 to 9 inches) produce the most desirable fragmentation. Blasting 
methods for the dislocation of stone are varied and generally are applied to meet local conditions. For this 
reason, differences in physical properties of granites necessitate the use of standard methods coupled with 
specific alterations in crushed-stone quarries in North Carolina. For details of blasting procedures used in 
quarries, the reader is referred to the many handbooks regarding the use of high explosives. 

THE TESTING OF GRANITE 

DIMENSION STONE 

Granite is among the most enduring of all building materials. Structures built of granite many cen- 
turies ago are still in good condition and should withstand successfully the detrimental effects of weather- 
ing for many centuries to come . Testing of the enduring qualities of granites is best accomplished by ob- 
serving the stone year after year during which time it is exposed to the naturally destructive effects of 
weather. Because this is impractical, various methods have been devised for the testing of stone whereby 
natural weathering processes are duplicated as closely as possible and accelerated in the laboratory. The 
most important of these tests is concerned with the effects on stone subjected to frost action and the chem- 
ical reactions produced by slightly acid waters, such as, rainwater and fog. 

Granites are porous to some extent. Tests have shown that medium-grained granites contain pore spaces 
equal to one-tenth of one percent to as high as five-tenths of one percent of the total volume of the stone 
(Meinzer, 1923). Water infiltrating the usually subcapillary sized voids is in large part trapped and re- 
mains essentially as a permanent pore filling. The repeated freezing and thawing, expansion and contrac- 
tion, of the contained water results in the development of incipient fractures and a subsequent enlargement 
and increase of the pore spaces within the stone by wedging of the mineral grains along cleavage planes and 
grain contacts. During periods of thawing, part of the trapped water may be released from the enlarged 
voids, but additional water reenters the pores, and the wedging action of freezing water is repeated. The 
enlargement resulting from the expansion of the liquid in the subcapillary voids also produces increased 
surface areas upon which waters can perform solvent action, and the feldspar constituents, together with 
any , undesirable accessory minerals (iron sulphides, etc.) present in the rock, will undergo chemical decom- 
position. The solvent action upon these minerals is reflected by the overall weakening of the stone, by chem- 
ical disintegration, and the production of unsightly iron oxide and other stains derived from the alteration 
of sulphide and iron oxide accessory minerals. It is interesting to note that granite in its natural state 
contains about 8 percent of water and is capable of absorbing 2 percent more; therefore, a cubic yard of 
granite contains approximately 3.5 gallons of water and will absorb about nine-tenths of a gallon more. 

The duplication of frost action is accomplished in the laboratory by saturating a test block of stone in a 
sodium sulphate solution at a temperature of 70° F. for a predetermined time, followed by a period of drying 
at 110° C. This test produces results corresponding to the action of alternate freezing and thawing. Some 
tests duplicating frost action require a deep freezing of the material followed by thawing at room tempera- 
ture, but tests of this type are not standardized. 

Unweathered granite is a very strong material. Crushing strengths ranging from 18,384 to 22,469 
pounds per square inch are encountered in the granite of the Mt. Airy district, and stone of related composi- 
tion in Rowan County is believed to possess equal strength. It will be noted that ordinary stone construction 
requires crushing strengths of 6,000 or more pounds per square inch; so, the dimension granites of North 
Carolina compare favorably and even exceed the strength required in any type of construction. The de- 
termination of crushing strength is accomplished by the use of specially constructed pressure machines 
into which are placed cubes or cores of the stone to be tested. 

Other tests of relatively minor importance include those devised for the determination of ratio of expan- 
sion and contraction, elasticity, resistance to shearing forces, fireproof properties, and color changes. For a 
discussion of the tests and the various testing media and machines, the reader is referred to the publications 
of the American Society for Testing materials. 



The Commercial Granites of North Carolina 55 



CRUSHED STONE 



The most common tests performed for the determination of the wearing and lasting properties of crushed 
stone include hardness, toughness, and soundness. 

Hardness: The hardness of stone is expressed as a coefficient value and is sometimes obtained by sub- 
jecting a core of the rock one inch in diameter to the abrasive action of a revolving steel disk over which 
crushed quartz sand (30-40 mesh) is passed. After 1,000 revolutions of the disk, the loss in weight (w) of 
the rock core is determined and the hardness factor obtained by the formula 20-w/3. In recent years, how- 
ever, the Los Angeles abrasion test has replaced this and other tests made for the determination of hard- 
ness of crushed stone. The Los Angeles abrasion machine consists of a steel drum 28 inches in diameter and 
20 inches long, mounted so that rotation is around the long axis of the drum. A radial shelf about 4 inches 
wide extends from end to end inside the drum. For the test 5,000 grams of sized crushed aggregate with 
12 steel spheres weighing 390-440 grams each are placed inside the drum and rotated 500 revolutions at the 
rate of 30-33 rpm. At the end of the test, the loss due to abrasion is determined by rescreening the original 
sample and computing the percentage of loss as related to the weight of the original aggregate sample. Such 
a test as that briefly described above is called the A abrasion test and is usually followed by the B and C 
tests during the comprehensive testing of aggregates. The Los Angeles abrasion tests are accomplished in 
the same machine but are independent determinations. Each requires a multi-sized aggregate and steel 
spheres of different total weights. Both the sizes in the aggregate and the steel spheres used are based on 
established standards. Results of Los Angeles abrasion tests of North Carolina granites from various local- 
ities are given in Table III. 

Toughness: Toughness as defined in a preceding section of this paper is determined by subjecting a core 
of rock one inch in diameter to the impact of a 2-kilogram hammer, falling from successively increasing 
heights of one centimeter until the core fractures. The height in centimeters through which the hammer is 
required to fall for fracture is taken as the toughness value for the rock. 

Table III. Results of Los Angeles Abrasion Tests on Some North Carolina Granites 

Rock 
Type of Test Described 

Name of Quarry ABC Location Page 

Balfour Quarry 25 26 31 Rowan 29 

Grassy Creek Quarry* 27 29 31 Granville 24 

Greystone Quarry 36 38 42 Vance 21 

Guil Quarry 40 42 43 Guilford 36 

High Point Quarry 33 35 37 Guilford 37 

Ivey Bluff Quarry* 32 31 34 Caswell 40 

McLeansville Quarry 23 24 27 Guilford 35 

Mt. Airy Quarries 52 54 53 Surry 45 

Neverson Quarry 31 32 35 Wilson 10 

Pearman Quarry* 50 50 51 Guilford 37 

Penrose Quarry* 29 27 32 Transylvania*** 49 

Person Quarry* 26 27 30 Person 44 

Lassiter Quarry 61 66 64 Wake 18 

W. E. Graham Quarry 25 25 27 Forsyth** 40 

Winston-Salem Quarry 48 51 53 Forsyth 34 

Woodleaf Quarry 32 34 36 Rowan 38 

* Non- Commercial Quarry 
** Biotite-gneiss 
*** Comparable to Henderson County stone 

Soundness : The soundness of crushed rock or its resistance to the action of freezing and thawing is de- 
termined in much the same manner as for dimension stone but is yet unstandardized. Usually, the sized 
and dried aggregate sample is immersed in a saturated solution of sodium sulphate, kept at a reasonably 
constant temperature of 70°F. for approximately 18 hours, removed, and dried in an oven at 105° to 110° C. for 
several hours. Following the oven drying, the sample is exposed to room temperature for several hours 
more. The chemical and structural effects of the action of the solution on the stone are determined after 



56 The Commercial Granites of North Carolina 

each cycle of the process by visual inspection and screening. The test duplicates the natural freezing and 
thawing processes of nature by the forces exerted on the liquid-filled pores of the stone during the crystal- 
lization of the dissolved solids contained in the sulphate solution. 

Mechanical Analysis: Tests for size and mechanical analysis of crushed stone are made by the use of 
square-opening sieves, conforming to United States Bureau of Standards sieve sizes. 

For details concerning the various methods of testing both dimension and crushed stone, the reader is 
referred to "The American Society for Testing Materials Standards," Part II, 1946. 

ECONOMIC ASPECTS 

ECONOMIC VALUE 

The utilization of stone resources, especially granite, in North Carolina has resulted in a mineral indus- 
try unequalled in size in the State. Since 1900, the value of quarried granite products in all forms has shown 
a continued increase, and in 1950 it approached an annual value of $8,500,000.00. This figure represents ap- 
proximately 32 percent of the total income derived from the sale of raw minerals and mineral products in 
North Carolina during the same year. In comparison, the 1950 production of industrial minerals (mica, clay, 
feldspar, pyrophyllite, talc), for which the State is well known, accounted for 35 percent of the total, an 
amount only slightly larger than that attributable to granite products. Therefore, as a mineral product the 
income from marketed granite surpasses that of other individual minerals and essentially equals the total for 
nonmetallics, excluding sand and gravel. 

Table IV shows the percentage relationships of the worth of granite products to the total value of ex- 
ploited minerals in North Carolina during selected years since 1900. It also reflects the direct relationship 
of income from granite quarrying to the mining economy of the State. The sale of crushed granite, of which 
North Carolina is the Nation's largest producer, is responsible for about 80 per cent of the total granite sales 
in the State during 1950. 

Table IV. Percentage Relationship of Granite Products to Total 
Value of Minerals Produced in North Carolina, 1900-1950 

Total Value 
Year All Minerals 

1900 $ 1,604,078 

1910 2,848,446 

1920 8,117,916 

1930 10,086,495 

1940 16,483,732 

1950 26,343,000 

MARKET VALUE AND TRANSPORTATION 

Dimension Stone : Dimension granite is a relatively high-priced commodity ; consequently, distance to 
market and cost of transportation are not generally considered important economic factors in the production 
of superior quality stone. This is especially true of stone unique to a particular area, such as, Rowan County 
and Surry County, from which pink and white granites, respectively, are marketable at high prices in many 
parts of the United States. Transportation costs for large blocks of granite are high, but quality stone de- 
mands a price which offsets the added expense of long-distance shipping. Current prices (1950) for block 
granite for the monument trade range from about $3 to $5 per cubic foot (160 lbs.) for rough stone, to $12 
and up for dressed stone. Prices for rough and finished building stone of corresponding quality run slightly 
lower. The Northeast and Central United States constitute the normal maximum distances to which North 
Carolina granite is shipped, but the pink variety from Rowan County has been marketed in recent years in 
Hawaii. The movement of dimension granite to these markets is about equally divided between rail and 
motor conveyance. Ordinarily, rough or unfinished stone is transported to finishers by rail and manufac- 
tured blocks are moved by motor freight to market areas. 





Percentage 


Total Value 


Value 


Granite 


Granite 


$ 294,000 


17 


839,742 


29 


1,968,912 


24 


3,473,406 


32 


4,125,518 


25 


8,500,000 


32 



The Commercial Granites of North Carolina 



57 



Crushed Stone: Crushed granite, in direct contrast to dimension granite, is a low-cost commodity in 
which the transportation factor is the primary economic consideration. This factor results from the wide 
distribution of many types of stone suitable for crushing and the availability of natural gravel in some areas. 
Because of this widespread availability of stone and gravel, the market for crushed stone is necessarily at 
close proximity to the quarrying operation and is usually a local product for use by local markets, seldom be- 
ing carried by trucks to points more distant than 30 miles or by rail more than 100 miles from the quarry. 
In North Carolina, however, crushed granites and related rocks from the Piedmont region are sometimes 
marketed in Coastal-Plain cities more distant from the quarry, a transportation factor brought about by the 
scarcity of crystalline rocks for crushing within the Coastal Plain Province. In order to meet competition, 
crushed granite is currently sold at prices ranging from $1.10 to $1.75 per ton delivered to consumer convey- 
ance at the quarry. 

PRODUCTION 

Dimension Stone : Production data for the early years of the stone industry in North Carolina are not 
available; however, it is estimated from incomplete statistics that a total of some 3,500 short tons, or 41,000 
cubic feet, of dimension granite were produced in the State during 1901. The calculated figure of short-ton 
production was determined by dividing the total value of dimension granite by an average unit value per ton, 
based on products from another granite-producing area, Barre, Vermont. The number of cubic feet produced 
was obtained by multiplying the figure estimated as short-ton production by twelve, the approximate number 




1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 

Figure 8 : Value of Granite and Belated Rocks in North Carolina, 1901-1950 



58 The Commercial Granites of North Carolina 

of cubic feet contained in a ton of granite. The number of cubic feet per short ton of granite is based upon 
a specific gravity of 2.60, a figure reduced slightly for convenience. 

Production figures for 1950 reveal a 700 percent increase (287,000 cubic feet) in both the production and 
value of marketed dimension granite. The substantial increase is attributable principally to the continued 
growth in popularity of the superior grade white granites of the Mt. Airy district and the pink granites of the 
Salisbury area in the building and monument industries. At present, these two sections are responsible for 
almost the entire output of dimension granite marketed by North Carolina quarrymen, production being re- 
stricted largely to rough and finished monumental and constructional stone and small quantities of curbing, 
paving block, and rubble. 

Crushed Stone : The increased use of crushed rock for concrete aggregate and highway construction, be- 
ginning early in the century, is now largely responsible for an annual production in excess of 5,000,000 tons, 
an increase of over 3,000 percent in less than 50 years. The products from crushed-stone quarries in North 
Carolina include various standard sieve sizes for highway construction, concrete aggregate, railroad ballast, 
and minor amounts for use in filter beds and for other domestic purposes. 

Figure 8 shows the combined annual value of dimension and crushed granite since 1900, and it reflects 
generally the relative production for the corresponding years. 

USES 

Dimension Stone: Dimension granite and related rocks quarried in North Carolina are used for four 
principal purposes. In order of market value, they are dressed monumental stone, dressed constructional 
stone, dressed architectural stone, and curbing. Additional uses, including utilization as rubble, paving 
blocks, and rough construction stone, constitute a small part of the production of stone from most of the 
dimension-stone quarries. The highest quality stone is used for monuments because most of it is polished, 
and polishing will accentuate any defects present in lower quality stone. Curbing material is the lowest 
quality, and dressed architectural and construction stone represent the intermediate quality from the quarries. 

Crushed Stone : In North Carolina, crushed stone is used principally for concrete aggregate, road metal, 
and other surfacing-material aggregates. The value of railroad ballast, the second most important use, con- 
stitutes about 10 percent of the total. Granitic rocks are especially adapted for these purposes, being chem- 
ically inert and generally less affected by abrasion than some other types of rock. Rocks, roughly classified 
as granite-gneiss, also constitute important crushed-stone sources in the State and were discussed in the de- 
scriptions of the individual areas where applicable. The crushed-stone producers of the State are equipped 
generally to supply crushed material of any desired size, washed or unwashed, according to demand. 



The Commercial Granites of North Carolina 59 

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